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Repairing Electro-Mechanical (EM)
Pinball & Coin Operated Games to 1978
Part Three

All text and pictures copyright by (Clay Harrell), 11/1/22.
Copyright 1998-2022, all rights reserved.

This document is a repair guide for Electro-Mechanical (EM) coin operated games made up to about 1978. This includes pinball games, pitch and bats (baseballs), bowlers, gun games, etc. Though pinball is stressed the most in this document, this information applies to most EM arcade games made from the 1930s to 1978. Electro-Mechanical (EM) means the game uses relays and switches, and does not use a computer CPU. This document is geared towards complete beginners. No experience is assumed, though basic electrical knowledge is helpful. The document should be read "top down" and in its entirety. (Well at least up to, but not necessarily including, part 3.)

Updates of this document are available at if you have Internet access. This document is part one of three - part one is here, part two is here.

For parts, schematics, and repair sources please see the parts and repair sources web page.

Table of Contents

3a. When Thing Still Don't Work: The Check List

So you're the impatient type, and couldn't stand to wade through all the above information and things to do. You want the bare essentials. Well this checklist is for you if your EM game doesn't work. Just follow this list...

  1. Make sure game is off.
  2. Verify the power outlet the game is plugged into works.
  3. Verify there is power at the wall outlet, and that power is getting to the transformer. Thirty year old (or older) power cords can easily have breaks in them. Check the AC voltage with your digital multi-meter (DMM) on the input side of the transformer.
  4. Check all fuses with your DMM. See the Check Fuses section. Check the fuse holders too, especially on Bally games.
  5. Make sure the coin door is plugged in (especially if a Gottlieb game). There's a plug just inside the coin door opening that attaches the coin door to the bottom relay panel.
  6. Check that there are credits on the credit wheel. If not, add some (manually if you must). Or better yet, make the game Free Play.
  7. Make sure coin door switches are not stuck closed!
  8. (Optional) Manually set the player one score reels to anything other than zero. This allows you to see if the game is able to reset the score reels to zero. Remember if score reels cannot go to zero, the game will never do a full reset/start.
  9. Verify the power switch is functional (if it has one, pre-1967 games generally don't.)
  10. Turn the game on. Some lights should go on. Remember on many 1970s Bally and Williams games you must press the left flipper button for the game to "light up", thus enabling the Lock relay.
  11. Lift the playfield and manually spin the score motor a bit. Does the score motor turn on and move to the next 'home' position? It should. (On Gottlieb games there is a 'home' position every 120 degree, on Bally & Williams games home is every 180 degrees.) If the score motor does not turn the game will never start. There may not be 30 or 50 volt power (blown fuse or bad fuse holder), or check the score motor's "home switch."
  12. Try the coin door start (replay) button.
    If nothing happens:
    • See the Reset Bank section (but make sure the game has credits or is on Free play!)
    If the score motor continues to run:
    • If the game has score reels, see the Score Reel section. If either of the two "zero position" switches on any score reel is out of adjustment, the score motor will continue to run.
    • If the game does not have score reels, see the Stepper Unit section. If a stepper unit does not reset, the score motor can continue to run (actually this can happen on games with score reels too), because the game cannot reset the stepper to the zero position.
    • If a Gottlieb game, make sure the score motor "brake" switch (a single switch on the score motor that has *no* wires attached to it!) is hitting the metal rod as the score motor turns. The purpose of this "brake" switch is to make sure the score motor stops at an exact home position and doesn't "over run", and continue running endlessly.
    • Check the score motor's "home" switch. On Gottliebs usually at 1C or 4C, on Bally and Williams games the "home" switch is usually on switch stack #1. This switch is what turns off the score motor when it rotates to a "home" position every 120 or 180 degrees. Because of the score motor's electro-motive force (EMF) when the motor turns off, the score motor home switch gets a "blue arc" every rotation of the score motor. (Easy to see when the score motor rotates!) The blue arc is *twice* the powering voltage due to the EMF that occurs as the magnetic field of the motor collapses when the power is removed. This blue arc makes the home switch wear and pit easily, and go out of adjustment. If the home switch is out of adjustment or worn, this too can make the score motor to "over run" a home position, and perhap never stop or start running!
  13. If the game starts and:
    • Blows a fuse. Either a coil is stuck on, or if a 70's Williams or Bally, see Bridge Rectifiers section. If it is a "GI" (general illumination) fuse, this won't usually stop the game from working - Just the playfield or backbox lights will be dead. There could also be, of course, a direct short somewhere.
    • A coil or score reel is stuck on, see the Score Relay Stuck On section. Often it is hard to see a stuck on coil. I always look at the bells or chimes to see if a plunger is stuck "up", in addition to the score reels. This usually means a playfield switch (or a relay activated by a playfield switch) is stuck closed, and it will prevent additional scoring of that point value or prevent the game from advancing to the next ball.
    • Certain features don't reset (like number of players, credit or ball number, etc.), see the Stepper Unit section.
    • Some game features don't work, see the Game Features section.

3b. When Thing Still Don't Work: Typically What's Wrong

At this point you have cleaned and checked the score reels, score relays, stepper units, and visually checked all the relay switches. Yet the game still doesn't work. Keep the faith, you are probably 75% done with your repair job at any rate!

Here's a list of some other common EM problems and their solutions:

  • No credits on game.
    Trying to start a game with no credits? A lot of people do not set their games to free play (especially if you bought it from an old vender!) Move the credit wheel to one or more credits and try again. Sounds simple, but you would be surprised how often that gets by you. Additionally check the zero position switch on the credit wheel, and make sure it is closed (telling the game that there ARE credits.) If this switch is dirty or mis-adjusted, regardless of the number of credits showing, the game won't start.

Credit unit on a Bally 4 Million BC. If the zero position switch is open
(or dirty), regardless of the number of credits shown, the game will never
reset via the front door start button.

Credit unit on a Gottlieb EM. Again if the zero position switch is open
(or dirty), regardless of the number of credits shown, the game will never
reset via the front door start button.

  • Plug the game in, but there's no lights and no power.
    This is a real typical problem on a game that has been in storage for long periods of time.

    Did you check the fuses? Sounds simple, but we all usually forget to do this.

    On most EM game, after the power exits the main transformer, it goes to a "hold" or "lock" relay in the bottom panel of the game. This relay usually has just one or two switches. If these contacts are dirty, no power will get to the rest of the game. Look for the most burnt relay in the bottom of the game cabinet, and that's probably the hold/lock relay! This relay is "on" the entire time the game has power. Clean it's contacts. With the power on, manually activate the relay (it should energize), and look for backbox/playfield lights. Also often the Hold/Lock relay's windings just burn and break, meaning the relay will never pull in. If this happens, the game will never start.

The Lock relay on a Bally 4 Million BC game. Notice how the paper wrapper
is brown from heat. This particular example isn't too bad - sometimes the
Lock or Hold relay can be so burnt it looks like it caught fire!

    Bally and Williams games often use a latch relay for the game over circuit that has one switch which controls all coil power to the game. If this one switch is dirty or mis-adjusted, the game just won't work! Clean and check the game over relay switches. On Gottlieb games pre-1976, there is a game over relay on a relay bank. It too controls all power to coils. On 1976 and later Gottliebs with Ax/Bx relays, there is a separate Game Over relay, and it loves to burn! (See the section on Continuous Hold relays for more info on that.) The relay works opposite of what you might think too... That is, when the Game Over relay is energized, the game is done (no coil power.)

The Game Over interlock relay on a Bally Fireball. Coils won't have power
if this relay has mis-adjusted switches, and the Lock relay may not hold.

    Power Switch and Power-On Lights?
    Keep in mind that pre-1967 EM's (especially Gottlieb's) usually don't have a power switch. On Gottlieb's in particular, you have to start a game to get the General Illumination (GI) lights to work. On Williams and Bally games (even as late as 1977), often pressing the left flipper button will turn the GI lights on (which turns on the Lock/Hold relay.)

    To by-pass the above "feature" of no GI when the game first powers on, I bend personally like to rig the game so the hold relay is ON. With Bally and Williams games, where the left flipper button turns on the GI lights, the flipper button switch will have two contacts. Again I like to bend the one switch that connects to the Hold/Lock relay permanently closed. This way when the game is powered on, the lights come on with the power switch.

Williams OXO. This game has the feature where if the game is turned on,
the general lighting is off until either a coin is dropped, or the left
flipper button is pressed. To make the game light up when the power switch
is toggled, I bend the left flipper switch which turns on the Lock relay
permanently closed (blue arrow.) Note the other flipper switch contacts
actually controls the flipper, so you don't want to adjust that switch.

    On Gottlieb games they never used the flipper buttons to turn on the Lock/Hold relay. Instead usually starting a game is how the Hold relay toggles on. This meant plugging in a Gottlieb game really did nothing - not until a game was started (either by inserting a coin or pressing the start button) did the game "light up." For my home this doesn't work for me. I want a physical power switch, and when the game is on the game should be "lit."

    Hence I rig the Hold relay so it's permanently "on." You can do this a couple ways like bending the switches closed, or rigging the armature so it's engaged. That's your choice, then I disconnect one wire lead that goes to the hold relay coil itself. This makes the GI lights "on" and stays "on" at power up. It also removes the power to the hold relay so it can't hum or get hot. There is a down side to this modification; if you shut the machine off in the middle of a game, when you turn it back on you'll still be in the middle of the last game. (Turning the machine off doesn't end the current game.)

    On those non-power switch games, I always add a power switch. To do this, just cut the black lead (hot) from the power cord as it comes into the game (before the fuse or transformer - remember the black power lead is "hot" on AC lines, where white is the return or common.) At this point I'm usually replacing the power cord too, using a dollar store 15 foot two prong extension cord. New two prong power cords are polarized, with a narrow and wide blade. The narrow blade is "hot", the wide blade is "neutral" (the "ribbed" wire on a new power cord.) Does it matter which line (hot or neutral) goes where? Technically no, either way the game will work fine. But for safety purposes the hot (black, narrow blade, smooth) should go to the fuse and power switch. This helps prevent a potental shock when the game is powered off, as the switch/fuse really turns off the "hot" side of the line cord.

An added power switch on a 1966 Gottlieb Hurdy Gurdy single player EM pinball.

    Next splice in a 5 foot length of line cord, connecting each lead of the new line cord into the cut. Route this wire to the front of the game. Drill a hole in the bottom of the cabinet, and mount a single-pole, single-throw (SPST) switch. It's not a bad idea to mount the switch in a piece of 3" x 3" x 3/4" thick plywood, and then mount the plywood to the bottom of the game with the switch trigger sticking through the bottom hole. This prevents the trigger of the switch from protruding under the game, where it could get damaged. Connect the two leads to the switch. There is a picture of this further down in the document under Gottlieb Coin Doors.

  • Check the coin mech switches in the coin door. This is especially a problem on Williams pinballs. If the switch that detects a coin drop is stuck on, the game won't work.

  • Check all the coin door wires. Many games will not even turn on or start if a coin door wire (or the coin door connector) is not attached. This especially applies to Gottlieb and Bally games.

The problematic Ax relay on a 1976 Gottlieb Target Alpha.
On these 1975 and later multi-player Gottliebs, it is very easy to knock
the Ax relay's switch blades out of the slots on the activator plate
(blue arrow.) This renders the game "broken", and is difficult to rectify
if you've never dealt with an Ax relay before.

The bottom panel where the Ax/Bx/Dx latching relays resides
on a 1976 Gottlieb Target Alpha.

  • 1975 and later Gottlieb game won't reset a game properly.
    These multi-player games replaced the reset bank with three latched relays called the Ax, Bx, (and Cx/Dx) relays. Single players use just an Ax relay. These latched relays have very little switch travel. They must be adjusted perfectly for the game to reset. It is very easy to distort the switches in these relays. If the actuator plate is man-handed, it can come off its pivot point. This may cause all the switch blades to come out of their corresponding slots. This can cause quite a mess, and the game will never operate until this problem is fixed. When the Ax/Bx switches come out of their actuator plate slot (usually because someone messed with it and unknowningly knocked the switch blades out), if they are not put back in the correct slot, the switch gaps will be all wrong and the game will never work. Note Gottlieb only used the Ax/Bx relays on multi-player games after 1975 Super Soccer (Single player games only use an Ax, another reason I prefer the simplier and easier to fix wedgeheads.)

  • The main solenoid fuse blows on 1972 and later Williams EM's and 1976 and later Bally EMs: Starting in 1972, Williams changed their pop bumper and slingshot kickers to operate on DC voltage. Bally also made this change in 1976, and Gottlieb did it on some EM game titles in 1978/1979 starting with Cleopatra (Pyramid.) This made these solenoids a bit more powerful and snappy (it is really noticeable on Gottliebs as the flipper coils were also DC, making them quite strong.) A silicon Bridge Rectifier was used to convert AC to DC. Unfortunately, sometimes this bridge shorts internally, and will blow the solenoid fuse or bridge fuse (or even the game's line power fuse) when a game is started.

    Note that Bally and Gottlieb used 1n4004 diodes on their DC powered coils (where Williams did not.) The diodes prevent EMF coil backlash from damaging the bridge rectifier. Williams didn't do this, and that's why it's more common to see Williams EM games with a shorted bridge rectifier than Bally or Gottlieb EM games.

Bridge Rectifier and capacitor on 1972 and later Williams' EM games (blue arrow.)
Shown below is the earlier type of bridge rectifier. Bridges you buy today will
look a bit different, but operate exactly the same. The bridge and the capacitor
convert AC voltage to DC.

Bridge Rectifier and capacitor on 1976 Bally Captain Fantastic.
This is a newer style bridge rectifier, and is used to convert AC to DC
voltage (pop bumpers are DC on this game.)

    Replace the bridge with a new 100 volt (or greater), 25amp bridge. For quick analysis, you can buy a 50 volt bridge at Radio Shack if you're in a pinch, but this is barely enough, but it will work. If the fuse blows that is situated right next to the bridge, check all DC components (bumpers, kickers, etc.) for a short. Often DC coils will have a 1n4004 diode installed on the coil (with the positive power lead going to the banded diode coil lug.) The diode prevents EMF from back flowing to the bridge rectifier, which shortens its life.

DC pop bumper on a 1976 Bally Captain Fantastic. A 1n4004 diode is used
on the DC coils to prevent EMF voltage back lash to the bridge rectifier,
thus increasing the bridge's life span.

3c. When Thing Still Don't Work: Buzzing/Noisy Relays and Coils.
    In most EM games there are momentary and hold style relays. Momentary relays activate (energize) for just a moment. Hold relays activate for long periods of time. Examples of hold relays include feature relays (that keep a set of lights or features activated on a pinball playfield). The "hold" relay on a Gottlieb game (which is energized the entire time the game is turned on). Bally also has a "hold/lock" relay that activates at power-on after the left flipper button is pressed.

    Hold and Lock relays are designed to be activated for a long period of time, without burning. In order to do this, the hold relay's coil will have high resistance (compared to a momentary relay). It should have 30 to 150 ohms. The higher the resistance the better (but the higher the resistance the less "pull" the relay will have).

    Hold relays, because they are energized for long periods of time, can be noisy. This buzzing is caused usually by one thing: the spring resistance of the relay is too high. Either the relay spring is too short/tight, or the relay's switch blades are adjusted to provided too much spring resistance. If a relay has to really work to pull in its activator plate, the AC 60 cycle hum will result while the relay is "holding". The AC 60 cycles sets up a vibration which causes the noise. AC means "alternating current", as the voltage goes from 30 volts, to 0 volts, to 30 volts again and again, 60 times a second. As the relay goes to 0 volts, the armature on the relay can release slightly, and then the voltage goes back to 30 volts pulling it back. This often causes the buzz or hum.

    Take a DMM and measure the resistance of the hold relay coil. It should be in the 30 to 150 ohm range. If there is the same relay coil number used elsewhere in the game, compare the two resistances, as they should be the same. If the suspect coil's resistance is lower, replace it.

    With time, hold relays can get warm (hot), and burn the insulation off adjacent windings. This will lower the overall resistance of the coil. Then the coil gets hotter due to lower resistance, and the cycle continues until the coil burns crispy and brown.

    Assuming the relay's coil has proper resistance and is not burnt, there are a couple things that can be done to minimize the buzz/hum. Adjust the relay with as little spring resistance as possible to pull in the armature plate. This will minimize the noise. Adjust the relay's switch blades and lengthen the spring so only the minimal amount of tension is needed to return the armature plate back to it's resting position. Even the contact surface between the relay coil and the activator plate can be filed to smooth it if it has wear. (Or just replace the activator plate and/or relay.)

    On Williams games there is a brass rivet on the activator plate. Sometimes this rivet is missing. This can also cause the hum. Or the rivet can become loose and that can contribute to the noise, though this is rare (usually the relay is just adjusted too "tight", causing the hum).

    Another hold style coil (though not a relay) are the flipper coils. If the player holds in a flipper button and the coils make a loud buzz, this can be often be fixed by replacing the coil stop. The coil stops on EM coils are slightly magnetic. This minimized the problem with the 60 cycles per second AC vibration.

3d. When Thing Still Don't Work: Gottlieb Reset Bank, Ax/Bx Reset Relays, Continuous Duty Relays.
    On Gottlieb games 1975 and earlier, the reset bank is the unit that gets the game started after the front door start button is pushed. If a game won't start and there's credits on the credit wheel (and the credit wheel zero position switch is closed), this is often a good starting point.

    Below is some history on the reset bank, and a list of things to check (last game using the reset bank was 1975 Gottlieb Soccer.) Starting in 1975 with Fast Draw/Quick Draw the reset bank was replaced on multi-player games with Ax (reset control), Bx (last ball), and sometimes Cx/Dx relays and a Coin stepper unit. Single players got just an Ax relay.

    It should be noted that Gottlieb was the company that utilized a reset bank for the start up procedure on multiplayer games. Bally and Williams didn't really use this technology (well they did, but in a different way and for different reasons, not for the start up sequence.)

A Gottlieb Reset bank on a 1974 Far Out.

Reset Bank.
The Gottlieb Reset Bank was used until 1975 (when it was replaced by the Ax, Bx {and sometimes Cx/Dx} latched relays on multi-player games, and just an Ax on single players). Super Soccer/Soccer (1/75) are the last multi-player game with a reset bank. Single players games got rid of the reset bank sooner; Pop-a-Card (3/72) and Space Orbit (4/72) were single player games with a reset bank (Grand Slam 7/72 does not have a reset bank.) Top Card (8/74) also had a reset bank. By 1975 the reset bank was definitely gone. The bank was eliminated largely for cost reasons.

The reset bank is basically a whole row of relays mounted in a metal rack with a master reset bar. When the reset bar is pulled (by its BIG 120 volt solenoid, top left in the above picture), all the relays are reset to a known state. This happens at the start of every game.

The Gottlieb reset bank includes several important relays that are crucial to starting a game. This includes the Game Over relay(s), Reset relay, Tilt relay, Start relay, and on four player games, player2, player3, and player4 relays. Make sure all these relay's switch contacts are clean and adjusted. In order to see any reset bank relay switches, you have to loosen the two wing nuts at each end of the reset bank, and "flip up" the bank.

Unfortunately, flipping up the reset bank is deceptive. When the bank is in operating position, many of the switches rest against the reset bar. But when the bank is flipped up, the reset bar is out of the picture. This can give false switch contact adjustment readings. Just be aware of this.

The main Gottlieb reset bank solenoid (the BIG one, upper left corner of the above picture) operates at 120 volts on many games! Also the start relay operates on 120 volts too. Keep this in mind when working on the reset bank. Don't shock yourself.

The Gottlieb reset bank must be positioned correctly, or the bank will bind
and not work properly. The rounded edges of the rotating reset bank should
line up perfectly with the rounded edges of the locking plate (as shown here
with the arrow).

    The Gottlieb "S" Start Relay.
    Almost every Gottlieb EM with a reset bank has an "S" start relay (single and multi-player games.) When this relay gets activated (by pressing the coin door start button), the game goes through its start-up sequence. Generally speaking, here is the start-up sequence:
    • Press the start button on the coin door. This completes the circuit to the start relay, and causes this relay to pull in and close some switches.
    • The score motor starts.
    • The score reels reset to zero through the start relay and the score motor.
    • Any feature relays or feature banks reset.
    • The reset bank solenoid pulls in, and resets all the relays in the bank.
    • The ball is served, and the game can begin.

    If you have cleaned and checked all the score reels switches and stepper units, and the game still won't start, check these things:

    • There could be no credits on the game; check the credit unit as there is a single switch on that unit which when open, will not allow a game to start.
    • On manual ball load games, there is a switch on the ball release hold mechanism. When the ball release coil is energized, this switch opens, and will not allow a new game to be started, until the ball release coil de-energizes (after the first points of the game are scored).
    • On Gottlieb games, make sure the coin door is plugged in. The game won't even turn on if the coin door is not plugged in.
    • Make sure the Hold/Lock relay is pulled in, and the switch(es) on the hold relay are working properly.
    • Gently rotate the score motor slightly with the game on. Does the score motor advance 120 or 180 degrees? Sometimes the score motor can get "stuck" in an "off" position, and manually rotating the score motor can be enough to awaken it (also check the score motor's "home" switch for pitting and mis-adjustment.)
    • A dirty switch on the "S" (start) relay, or game over relay(s), or reset relay(s).

    If there are credits, flip up the reset bank, and clean and check all the switches on the "S" and game over relay(s). While you're at it, clean/check ALL the switches in the reset bank. If the score reels are OK, it's almost a given that your Gottlieb game start up problems lie in a switch in the reset bank.

    If a Gottlieb game will not start with the coin door replay button, try manually resetting the reset bank. This will often be the kick that gets a game awake from the dead. Or manually release the S relay on the reset bank (it's a "reach around" type thing.)

Gottlieb Target Pool's reset bank. Here the start relay can be seen,
along with the S relay's armature switch.

Gottlieb Target Pool's reset bank, flipped up. Here the S relay's armature
switch has a better view.

    The Gottlieb Armature Activated Start Relay Switch.
    Another particularly nasty animal is the Gottlieb armature activated start relay switch. This switch lives under the start relay, and can't be seen unless the reset bank is lifted. Unfortunately, it is difficult to see and adjust this switch unless the reset bank is down. So how do you see and adjust the switch? On 1967 and later reset banks that rotate, it's not that bad. But on the earlier games, you really can't access the S armature switch without unbolting and removing the entire reset bank from the bottom panel!

    Often this switch is dirty or mis-adjusted. If mis-adjusted, the game won't start properly: the score reels and feature banks will reset, but the start sequence just stops there. So it's a pretty important (and over-looked) switch! The switch is activated by the armature mechanism that trips the Start relay. It is labeled on the schematics as the "S Armature" switch. This armature switch was used mostly on Gottlieb single player games (not seen as much on multiplayers.)

Gottlieb coin unit (left) and Ax (reset), Bx (first ball), Dx (last ball) relays in a
Target Alpha 4 player bottom cabinet. This rig was used on multi-players after
Super Soccer in 1975. The Ax/Bx short throw latch relays are a major
headache in 1975 and later Gottlieb multi-player games, as the switches must be
adjusted *perfectly* for the game to operate correctly. The coin unit tells the game
how many coins were inserted for the current game (how many players are playing).
The backbox's player unit keeps track of the current player and ball number
being played.

    Gottlieb Single Player Games without a Reset Bank (1972-1978).
    Single players games got rid of the reset bank around 1972. Pop-a-Card (3/72) or Space Orbit (4/72) were the last single player games with a reset bank (Grand Slam 7/72 does not have a reset bank). The reset cycle on these 1972 and later non-reset bank games is pretty simple:

    • Pressing the coin door replay button. (This assumes there are credits on the game!) The start relay will pull in. (If this does not work, the start relay on the bottom board can be activated manually.)
    • A switch on the start relay causes the hold relay to pull in and lock on. This turns on the playfield lights and completes part of the power path to the playfield solenoids.
    • A switch on the start relay causes the score motor to turn.
    • A switch on the start relay and the score motor causes the ball count unit to reset (to position zero).
    • If the game has drop targets or a playfield relay bank, a switch on the start relay and the score motor will cause these to reset.
    • A switch on the start relay and score motor pulls in the V reset relay (an interlock relay). A switch on the V relay causes the start relay to de-energize (the start relay was energized for just an instant while all the previous steps occur).
    • A switch on the V relay and the score motor (which is still turning) causes the score reels to reset to zero.
    • As soon as the score reels reset to zero (closing all the score reels zero position switches), the Vr relay pulls in. This releases the V relay (the V relay was locked on for a few seconds as the score reels reset to zero).
    • If there is a ball in the outhole (closing the outhole switch), the Ball Return relay pulls in for an instant. A score motor switch and a switch on the Ball Return relay will energize the outhole kicker, and kick the ball from the outhole to the shooter lane.
    • The score motor will stop running as soon as the Ball Return relay de-energizes.
    • As the ball rolls into the shooter lane, the ball rolls over a switch which closes for an instant. This advances the ball count unit from the zero position to the ball one position. A switch on the ball count unit then closes which turns on solenoid power on the playfield.
    • The game is now ready to be played.

    The ball count unit is a potential problem in this reset sequence. When the ball count unit is at the zero or six (game over) position, a switch is opened which does not allow power to any playfield solenoid. So the increment of the ball count unit to ball one turns on all the playfield solenoids. Likewise, the game is over when the ball count unit moves to position six (this again opens a switch and turns off the power to the playfield solenoids, and turns on the "Game Over" backbox light).

    If the game resets, but none of the playfield solenoids work, there are two likely culprits. First is the hold relay. There is a playfield solenoid power switch on the hold relay. Second is the ball count unit. If the zero position switch does not close when the ball count unit is advanced to ball one, no power will go to the playfield solenoids.

    Gottlieb Ax/Bx Latch Relay Adjustment.
    In 1975 when Gottlieb abandoned the reset bank in favor of the Coin unit and Ax/Bx relay setup on multi-player games, this made game repair a bit more challenging. The big problem with the Ax relay is the lack of switch travel. This means the switches on these latch relays must be adjusted perfectly or the game will not reset. For example, the score motor will continue to run, and the game will never finish its reset cycle if there's an Ax/Bx/Cx/Dx relay problem.

    Adjusting these Gottlieb latch relays is more of an art than a science. It takes some practice, and some experimentation to get it right. I can offer some suggestions that should help. First is make sure the switch stacks are tight before you do any switch adjustment (this applies to all relay switch adjustments.) Next make sure that the moving blades have enough back pressure to snap the armature plate to "home" when the latch releases the armature plate. The armature should not come back "soft", but should make a noticeable click. This ensures the most switch travel and precise activation of the armature plate. Last you need to adjust the switches. No rocket science here, just make sure you get as much wiping motion as possible on the switch contacts, without making the contact too close together when the switches are open.

    Gottlieb Latch Relay Problems.
    Starting in the early 1960s (maybe first with Flipper Parade), Gottlieb used latch relays for playfield features. They used these up to the 1970s with their Baseball wedgeheads like Playball and Pro Football. These are different than the short stroke Ax/Bx latching relays, in that they use longer switch blades. Unfortunately sometimes this style of latch relay does not reset or "unlatch".

    There are two causes for this. First is the contact of the two latch plates is too great. That is, you only need just a little bit of the "lip" to catch and latch. Less lip, and it's easier for the relay to pull the latch plate in, unlatching the relay. To adjust this just bend the latch stops so there's as little plate as possible latching to the two latch plates. This means there's less work the relay has to do to pull in the latch plates, and less chance magnetism will effect the plates.

Gottlieb Latch Relay: The red arrows show the latch stops that can be bent
to adjust the plates so there's minimum contact. If that doesn't make the latch relay
work reliably, add a copper rivet to the latch plate. See how the plate rides on the rivet
instead of the adjacent latch plate. This avoids magnetism problems. Pic by Tim M.

    The next problem is residual magnetism, which can make the latch plates stick. If the above adjustment does not work, a brass or copper rivet (non-magnetic) can be added to the one latch plate to prevent this problem.

Modifying the Continuous Duty Relays for No Burn, as used in Ax/Bx Games.
    Starting with Fast Draw/Quick Draw in 1975, Gottlieb felt the reset bank unit was too costly, and looked for a less expensive replacement. The result was the Ax (reset control) and Bx (last ball) latch relays. Also implemented was the continuous duty Tilt-hold "H", Gameover "Q", and First-ball "U" relays. By continuous duty I mean these relays are always energized when the game is in "game-over" mode (like the old school "H" hold relay, before 1975).

    The list of problems with this setup are immense. First the Ax/Bx relays have very little switch throw, yet must be adjusted perfectly for the game to reset, start-up, and end. The make/break switches on these two latch relays are very hard to adjust perfectly.

    The next problem are the three continuous duty relays. These are A-9736 (First-ball), A-9738 (Tilt-Hold), A-9740 (Game-over) relays, which are all basically 25 to 35 ohm relays (old school R20-5.) When these games were new, this setup probably worked fine. But now that these games are 30+ years old, these relays are usually baked and fried. These can be replaced with the same relays, but why do that? (Other than to make Steve Young smile!) A great idea is to use a Gottlieb System1 and System80 ORANGE coin door lockout relay coil A-16890 (220 ohms) to replace the low-ohm relay coils (anytime you get a system1 to system80 up to Hot Shotz in your shop, steal the coin door lockout coil, which isn't being used anyway!) The A-16890 relay coil will never burn at 220 ohms, and consumes a lot less power in the process. But at 220 ohms, it's not strong enough to work with the 25 volts AC used in EM games. So these relay coils can be half-wave rectified to DC, making them plenty strong enough. Gottlieb actually started to do just this on the last EM games like Joker Poker.

Using the A-16890 relay coil for continuous duty coil as shown here. Note the
capacitor and resistor really isn't needed, but the two 1N4004 diodes are required.

Here's why the continuous duty relays should be replaced on a 1975 to 1979
Gottlieb pinball. These are the Game Over, 1st Ball, and Tilt-Hold relay coils
(A-9740, A-9736, A-9738 relays respectively).

Here's a stock Game Over "Q" relay on a Gottlieb Fastdraw. Notice how burned it is. Gets very hot because it's only 30 ohms and energized continually.

Here's a replacement A-16890 relay (220 ohms) with two added 1n4004 diodes. This
modification works great and the relay will not get hot and destroy itself.
Note the black power wires go to the non-banded diode coil lug. And the
orange jumper wire has been replaced with a 1n4004 diode. This was done on both
the Game over and First Ball relays in this manner. (Often a 47 mfd cap is needed too.)

Here's a replacement A-16890 relay (220 ohms) with two added 1n4004 diodes on the
Tilt-Hold relay. This implementation is slightly different than on the Game Over and
First Ball relays, but the electronic principle is exactly the same.

    The solution is to use the orange A-16890 relay as a DC coil. That is, leave the 1N4004 diode in place on the relay, even though you're installing this relay in an EM game. Attach the BLACK relay coil wire(s) to the NON-banded (anode) diode lug of the relay coil. Then use another 1N4004 diode and attach the BANDED diode end (cathode) to the other lug of the relay coil. And finally attach the game's relay coil signal wire to the other end (NON-banded side) of this added diode. So basically the banded ends of the two diodes "point" together with their bands connected at one of the relay's coil lugs.

    What this does is effectively converts the AC power to DC in a half-wave format, but just for this relay. This allows the A-16890 relay to work in an EM game. (If you don't use the diodes, this relay will chatter and not work.) This continuous duty relay coil will never burn up, and consumes a lot less power in the process. Gottlieb adds a 50 mfd 50v capacitor (installed on the coil lugs parallel to the coil diode, with the cap's "+" lead connected to the diode banded lead) and a 6 ohm 2 watt resistor (in front of the second diode) to the circuit too. The resistor is not needed, but usually the 50mfd capacitor is needed (especially if the game is not hi-tapped.) For example if the Game Over relay has a hard time "pulling in" or chatters, add the capacitor across the lugs of the relay (positive cap lead to the relay lug with the banded diode leads.) Note I have also seen where the game won't go to "game over" (which requires the Game Over relay to lock-on) if this capacitor is not present - instead the score motor just keeps running as the Game Over relay tries to lock-on.

3e. When Thing Still Don't Work: Video on Ax Relay/Reset Banks
    Movie Explaining Gottlieb Multiplayer Ax and Reset bank Setups.
    Below is a 6 minute movie I made explaining the reset bank and Ax relay setups on multiplayer Gottlieb pinballs during the 1970s. This should help with understanding and adjusting a Gottlieb latch relay like the Ax/Bx/Cx/Dx relays. This is a 640x480 movie file.

3f. When Thing Still Don't Work: Score Motors and Other Motors
    I'm sure you've noticed by now that there's a motor in the bottom on your EM pinball cabinet with lots of switches. This is known as the score motor. It's job is to activate relays repeatedly until a feature or job is accomplished. If a job can't be accomplished (for whatever reason), often the score motor won't turn off. It just won't quit until the job at hand is completed!

    Because of this, score motor switches take a lot of abuse, and often need adjustment. As you get experience fixing EM's, you'll probably inspect/clean all the score motor switches as a rule. Particularily on Gottliebs, the switch contact gap distance can be critical in making a game work. The score motor is often all about timing, so things like motor RPM and switch gaps are sometimes important. Because of this, avoid any switch adjustment until you have increased your score motor experience a bit.

    Many beginner EM fixers want to adjust the score motor switches because the score motor won't stop running when a game is attempted. However, the score motor is running because a switch somewhere else is causing this problem! Typically it's a switch that should have opened in the score reels (zero position switch) or in the score relays. The motor running continually is usually the result of something else - that is, the problem is usually not on the score motor itself.

A Gottlieb score motor, top view ("2001", 1971.)
The blue arrows show the original marking for one of the switch stack numbers
(from 1 to 4). Note the broken motor brake switch at 3 1/2. This is a single
switch blade with no wires or contacts. Its purpose is to stop the motor from
"over running" at home positions. It's a back up brake, and usually not needed.

    Because the score motor has several different levels (cams), and many switches associated with each cam, a numbering system was created to identify the switch stacks. This number format is usually shown on the game's schematics. On Gottlieb score motors, numbers are used to identify the switch mounting brackets (usually from one to four). Letters are used to identify the switch stack's level (cam), with "A" being the level closest to the bottom board, and "E" closest to the playfield. If the schematic referred to switch "4C", this meant the switch was located in the switch stack mounted on bracket number four, and was the "C" (middle) level. Note there could be as many as five or six individual switches on the switch stack 4C! In order to find the exact switch in question, the schematic also identifies the switch's wire colors (and hopefully the game's wire colors have not faded!)

A Gottlieb score motor stack numbers explained ("2001", 1971.)
Note the blue arrow showing the switch stack lettering.

A Gottlieb score motor, side view. Here the switch letter levels
can be clearly seen ("A" is closest to the bottom of the picture).

    Bally and Williams used a different numbering scheme for their score motor. Mostly because they have a different style motor than Gottlieb. Gottlieb's was like a record player, where Bally and Williams was more like a drum unit. The number system is easier for Bally and Williams though, more obvious. (At least to me!)

Williams score motor (Grand Prix 1976.)
Uses the same switch stack number scheme as Bally, except there's two stacks labeled
"impulse" (right side) and an "index" stack (left side.)

Bally score motor (Fireball 1972). Note the numbered cams.

Bally score motor cam and switch stack scheme (Bally Gator).
Again the "A" switch is closest to the bottom board.

    Chicago Coin's score motor was more Gottlieb-ish, but they too had a different number scheme. Kind of the reverse of Gottlieb, with the stacks being lettered (instead of numbered), and the switches within the stacks having a number. I guess everyone had to do something different (though I'm not entirely sure why that is!)

Chicago Coin score motor (Sky Rider 1974.)
Note CCM uses plastic cams on their score motor.

Chicago Coin score motor switch stack numbering (Sky Rider 1974.)
CCM does it in reverse from Gottlieb - Stacks are labeled "A" to "E",
and each switch is numbered within that stack.

    Getting to those Pesky Score Motor Switch Contacts.
    Score motors usually have cotter pins to allow you to release and hinge up the motor, making some switches easier to get at (of course the switch that needs to be adjusted or cleaned will never be one of those switches!). Most have cotter pins or screws to allow you to remove the whole thing away from the frame for better access. They also usually have a disconnect plug to stop the motor from turning. This can be useful in really in-depth troubleshooting; you can try and make the sequence happen slow enough to watch what is happening by using this plug as an on/off switch for the score motor.

    Lubricating a Score Motor.
    The only part that needs lubricated on Gottlieb score motors is the felt needle bearing pad. This is accessed via a small hole on the bottom of the score motor. Just put a couple of drops of 3-in-1 oil on this pad. No other lubrication is needed! For example, do *not* lubricate the brass gears of the score motor. Brass on brass gears are designed for no lubrication. Same thing with nylon on nylon gears, and nylon on metal gears, use no lubrication. Remember the EM rule of lubrication, if in doubt, do not lubricate.

Shown here is the bottom of a Gottlieb score motor,
and the oiling hole for the needle bearing felt pad.
The score motor is tipped up for this photo (most Gottlieb
score motors have a hair pin that allow the motor to be tilted).
The bearing pad can be lubricated with a few drops of 3-in-1 oil.
Do not lubricate any other parts (especially the exposed
brass gears).

    The Score Motor's Home Switch.
    Check the score motor's "home" switch (on Gottlieb's, usually at 1C or 4C, and usually switch stack number 1 on Bally and Williams.) This switch is what turns off the score motor when it rotates to a "home" position every 120 or 180 degrees. Because of the score motor's electro-motive force (EMF) when the motor turns off, the score motor home switch gets a "blue arc" (easy to see when the score motor rotates!) every rotation of the score motor. The blue arc is *twice* the powering voltage due to the EMF that occurs as the magnetic field of the motor collapses when the power is removed. This blue arc makes the home switch wear and pit easily, and go out of adjustment. If the home switch is out of adjustment or worn, this too can allow the score motor to "over run" a home position, and perhaps never stop running! On the other hand, when the score motor starts running due to another switch, the home switch may be so pitted and dirty it will not allow the motor to run to the next home position. This will often freeze the game and not allow it to play. Hence it is absolutely necessary to make sure the home switch is clean and properly adjusted on any EM game.

    Score Motor Brake.
    On Gottlieb games, there is also a "brake" switch. This is easy to identify; it's the score motor switch with no wires attached! It's purpose is to stop the score motor from "over running" a "home" position. If this switch is broken, this can also cause the score motor to over shoot a home position, and to continue running endlessly. Other makers use different brakes. Often the needle gear will disengage after power is removed from the score motor, not allowing the motor to over-run. Bally and Williams used a different brake system where the motor's armature disengages from the gear box when power is cut to the motor. This way the armature can continue to spin without turning the gears.

    CCM Score Motor Carousels.
    Chicago Coin games from the 1960s onward used plastic carousels on the score motor. (Gottlieb used metal.) This is fine except for one problem - how the carousels tighten to the motor shaft. There is a single screw that does this, and if tightened too much, it will crack the plastic carousel's mounting neck. This renders the score motor useless, as the motor turns and the carousels do not.

CCM score motor with plastic carousels.

Side view of a CCM score motor with plastic carousels.

Copper 3/4" x 1/2" reducer, bought at Lowes.
This piece goes over the CCM plastic carousel neck,
allowing it to be tightened to the motor's shaft.

Rear view of the cracked score motor carousel and the new copper sleeve
that will fix it.

    This is a common problem, but luckily one that is easy to fix. It involves going to Home Depot or Lowes and getting a copper 3/4" x 1/2" reducer (Lowes sku #0 39923 32064 3). Then a 1/2" portion of the thicker part of the neck is cut off. A 5/32" hole drilled in this collar. The metal collar is put over the cracked portion of the carousel, and the screw goes through the hole. Now the carousel screw can be tightened as much as needed, and the score motor is saved from the junk pile.

    Score Motors in the Schematics.
    The next section discusses score motors and how they are implemented into the schematics. Scroll down or click here to continue to that section.

    Different Motor Types.
    If a game has a bad or missing motor, it can be difficult to find a correct replacement. Here are some things to consider when choosing a new motor:

    • Motor voltage (typically 50 or 24 volts AC).
    • Motor spin direction. AC voltage motors cannot have their direction easily changed!
    • Motor spin RPM.
    • Motor shaft size (1/4", 5/16", or 3/8" are the most common sizes) and length.
    • Threaded mounting positions on the gearbox and other motor mounts.
    • Motor winding resistance.
    • Motor/Shaft orientation. Is the output shaft opposite of the motor's frame, or on the same side of the motor?
    Sometimes a 50 volt motor can be made into a 24 volt motor by unwinding some of the windings around the motor's layered plates. Do this carefully, as the total resistance of the motor's windings should never be less than about 2.5 ohms, otherwise it will be a "short" and no longer a motor. Don't forget to sand the painted insulation off the end of the new wire end before trying to solder it to the motor's wire lug.

    Fixing a Burnt Motor.
    Burnt windings can be replaced by hand on a motor. This is not an easy task, but it can be done. First using a micrometer, measure a single wire diameter of the original (burnt) motor windings. Then find a coil with the same size wire diameter. Now unwind or cut all the burnt windings off the motor, and re-wind the motor's windings using the wire from the donor coil. Yes this does take a while, but you don't have to be squeaky clean with your new motor windings. Total resistance of the new windings should probably be in the 4 ohm range. (If you know someone with the same game, get them to measure a good motor's resistance and try to match that.) Don't forget to sand the painted insulation off the ends of the new wires before trying to solder them to the motor's wire lugs.

    Slow and Sluggish Game Motors and Score Motors.
    This information applies to any motor in a pinball, baseball pitch and bat, gun game, fortune teller, or any other EM arcade game.

    If a game is having a hard time resetting the score reels (they reset slowly), this is usually due to a sluggish or slow score motor. Other game motors (as used in EM arcade games) may be slow and sluggish too. This happens because the grease inside the motor solidifies with time. If this happens, often the motor may need to be taken apart and re-lubricated. Also sometimes the gears inside the motor strip. If this happens new gears will be required (donor motors can be used as parts).

    First step is to remove the motor from the game. I can't really give specifics on how to do this, as it is often different from game to game. But the motor will need to removed and isolated from whatever it is driving. Usually the motor is mounted to some sort of metal frame with four machine screws. The two power wires will of course need to be desoldered from the motor's lugs. Any motor switches should be attached to the metal frame and not the motor itself.

    If the motor is sluggish (before "splitting the case"), often the gear box can be soaked in alcohol or white vinegar. This can often break down the solidified grease, without taking the whole motor apart. The downside is no new lubrication can be added this way. Just let it soak overnight and see if that helps. Sometimes it works, but usually I find myself splitting the motor case anyway for a good cleaning and re-lubrication.

    Splitting the Case.
    First remove the motor from the gear case. This is not always possible (depends on the motor), but it is very helpful if it can be done. On most motors other than Multi-Products motors, it's usually just two machine screws that hold the armature to the motor, and the motor itself from the gear case. (Note Pinball Resource now repairs Multi-Products motors.)

    Be careful when removing the motor from the gearbox. Often there is a small lightweight spring on the armature, along with a brass bushing. Don't loose these parts! The spring is used to push the armature gear away from the first gearbox gear. This way when the motor first powers on, it does so in a "free-wheel" mode. As the motor comes to full power after half a second, the armature is pulled towards the center of the motor's layered frame plates. This compresses the spring and engages the armature to the gearbox. Likewise when power is removed, the spring pushes the armature gear away from the first gearbox gear, causing the gearbox to immediately "stop on a dime".

The motor has been removed from the gearbox.

    With the motor separated from the gearbox, to get inside the gearbox case, the case will need to be split. The gearbox case is often riveted together. If this is the situation, grind the face off one side of the rivets using a Dremel tool, and knock them out with a punch and a hammer. Some gearboxes use screws which can be easily removed.

Here the four rivets have been ground and knocked out.

    After the rivets or screws are out, the top half of the case can be removed, exposing the gears. Remove the gears ONE AT A TIME and clean them with alcohol. Be careful, take notes and digital pictures, so the order and position of the gears is documented. Clean the gear case behind the gears too (and of course clean the removed half of the gear case). Re-lubricate the gears with a *light* coating of Super Lube Teflon Lub Gel.

The top half of the gear case cover has been removed. This motor looks
pretty good - not much solidified grease here. But remove each gear, one
at a time, and clean it with alcohol.

    Re-assemble the gear case. Replace the rivets with some old EM switch stack screws and nuts! These work great and are the perfect size (I believe they are #4 threaded bolts.)

    The Motor's Brake.
    Now check the armature. Many motors have a built-in brake system. This is done so after the power to the motor stops, the motor cannot "coast" past a certain switch position. Gottlieb, for example uses a switch blade as a brake, mounted on the score motor's frame. They are the only company I know of that does that. Most other companies (especially Williams) use a spring loaded armature. As power is applied to the motor, the magnetic force pulls the spring loaded armature towards the motor's layered plates. This engages the armature to the gearbox, and the gears turn. As power is turned off to the motor, the spring pulls the armature back to the resting position, which disengages the gears. This allows the armature to coast (continue spinning) without turning the gears.

    If your motor has this spring loaded armature system, it is *very* important to check that this is working! If the spring is broken, the motor can coast past the position it was intended to stop. This can cause all sorts of problems (like a motor that never stops running, or game features that don't reset properly).

    If the armature spring is broken, it can be easily replaced. But don't use too strong of a spring, or the gears may never engage (or not engage fully, causing the armature gear to strip the first gearcase gear). If the spring is too weak, it won't dis-engage the motor from the gearbox. It's all trial and error. I personally keep both a 30 and 50 volt AC transformer on my work bench just for testing motors. This is very handy when having to replace the armature spring, as I can see on the work bench if the armature brake is working correctly.

    Motor Repair for Hire.
    I received this email from Multi-Products regarding motor repair (Multi Products is the company that made most of the motors used in coin operated EM games.)

      From: Mark Patzke 
      Subject: webpage
      Date: Mon, 18 Oct 2004 20:28:19 -0500
      I was looking at your web page about parts and repair 
      resources and would like to let you know that I can 
      still repair just about any motor that we have made 
      throughout the years. As for ones that weren't ours, 
      I can take a look at them and give a quote to repair 
      if I able to.
      Mark Patzke
      Multi Products Co. Inc 
      Unfortunately Multi-Products has stopped this service about 2010. Now Steve Young of the Pinball Resource is doing all Multi-Products motor repair. Contact him with rebuild concerns and questions.

3g. When Things Still Don't Work: Start-Up Sequences (Reset Sequences)
    Starting in the early 1970's, "operation manuals" became available from EM game manufacturers. These manuals outline a "start-up sequence". This is the sequence of events that happens after you press the game's start button. If your EM game doesn't start up properly, this sequence of events can help determine the problem.

    The start-up sequence is game specific, but generally can be applied to most games. This is helpful especially on older EM's where there is no operation manual.

    The following start-up sequences were outlined from mid-1970's games. They may not apply to the game you're fixing. But they will give you a general idea of what an EM game does when you press the start button.

    Bally Start-Up Sequence.

    1. Coin is inserted into the game. The coin relay will energize. It will stay energized through its own hold-in switch and a score motor switch. If the credit button is pressed (instead of a coin being inserted) and there are credits, the credit relay will be energized which energizes the coin relay.
    2. The coin relay will energize the lock relay (this turns the general illumination on). The lock relay will stay energized through its own hold-in switch and a delay relay switch.
    3. The coin relay will energize the reset relay, through a game over relay switch (if your game won't start, try cleaning the contacts on the game over relay; a very common Bally problem).
    4. The score motor will operate. This will energize the score reset relay(s). The score reset relay(s) will attempt to clear the score reels to zero. This is done by operating the score motor. Each turn of the score motor will operate the reset relay once, which in turns moves a score reel one position, until the score reel(s) are at zero. If the score motor continues to run when a game is started, there's a good chance the zero position switch on the score reel(s) is dirty or mis-adjusted.
    5. The coin relay, through the score motor, will advance the total play meter.
    6. The reset relay, through the score motor, will reset the stepper units (zero the ball count and player units).
    7. The coin relay, through the score motor, will decrement the credit unit.
    8. The coin relay, through the score motor, will energize the game over latch relay coil.
    9. The coin relay, through the score motor, will energize the 100,000 relay latch coil(s) (if the game supports scores greater than 99,999).
    10. If the outhole switch is closed (single ball games) or the ball trough switches are closed (multi-ball games), a ball is released to the shooter lane through the outhole relay (single ball game) or ball release relay (multi-ball game) and the score motor.
    11. On multi-player games, the credit button may be pushed again to add a player. This time the coin relay will not energize the reset relay. Instead it will (through the score motor) advance the total play meter, decrement the credit unit, and advance the coin unit.

    More Bally Start-Up Sequence Info.
    Taking the Bally sequence a step further, here is the sequence for a common multi-player game like Captain Fantastic.

    1. Coin inserted into game closing 1st coin switch. The coin relay will pull in.
    2. Next the reset relay pulls in. The reset relay will stay energized until all score reel zero position switches are open (signifying all the score reels have reset to "zero".) On a four player game there are 16 of these switches hooked in parallel.
    3. In the backbox there are two score reset relay which pulse, due to switches on the score motor. As these pulse they energize the non-zero score reel coils, getting all the score reels to the zero position. This is handled through the score motor 2A and 1C switches, which pulse the two score reset relays.
    4. On the reset relay switches will reset the player unit (in the backbox) and the ball count unit (on the bottom board), and the game over latch relay (taking the game out of "game over" mode.)
    5. If the bonus stepper unit (mounted under the playfield) is not at reset position, the Bonus Score reley will energize. Using score motor switch 2B and the bonus unit reset coil, the bonus unit should get to the zero position until a switch on the bonus unit opens.
    6. With the score reels and bonus stepper reset, the Reset relay should de-energize and the score motor should stop.
    7. Now the ball, which should be in the outhole (closing the outhole switch), should pull in the outhole relay. This will again start up the score motor, using a switch on the motor and the outhole relay to kicks the ball to the shooter lane. The outhole relay will also increment the ball count unit if the Ball Index relay is energized. (As soon as a point is scored, the ball index relay energizes.) This is no different than a ball drain during game play.

    1950s Gottlieb Start-Up Sequence.
    This applies to single player Gottlieb pin games without score reels (light box scoring), from Triplets (7/50) to Ace High (2/57). These games have no game over relay, and there is power to the playfield at all times (even when the game is over, so a patron can still operate the flippers after a game is finished). Backbox scoring (no score reels) single player games Royal Flush (5/57) to Dancing Dolls (6/60) basically also operate the same, except they have a "game over" relay to kill power to the playfield after the last ball has drained.

    1. Insert coin or press the "Replay Button" coin door start button (if credits are available - the zero position switch is closed on the credit unit and score motor switch 1C is closed). Another manual reset method is to reset the Points unit by hand, and then reset the 100,000 unit by hand - this will cause a game reset too (but no credits will be removed).
    2. The "S" start relay trips (this is often located on an under playfield bank). This is a 120 volt relay.
    3. If the game has trap holes, a switch on the Start "S" relay will energize the Shuffle coil and release the trapped balls.
    4. Using the same Start "S" relay switch above, the Points unit will reset to negative one ("-1 pos"), assuming the Points unit is not already at the reset position.
    5. Using the same Start "S" relay switch above and a Point unit reset position switch, the 100,000 unit is reset to the negative one ("-1 pos") position, assuming the 100,000 unit is not already at the reset position.
    6. Again with the same Start "S" relay switch closed and score motor switch 2C, a credit is subtracted from the credit unit and the mechanical game counter is incremented.
    7. With the 100,000 unit at the negative one position, and using a switch on the Start "S" relay and score motor switch 4C, the under playfield bank is reset. This will un-trip the Start "S" relay.
    8. With the 100,000 unit still at the negative one position, the score motor turns on.
    9. With the Points units at the reset position, the ball release tray solenoid pulls in (dropping the balls to the ball trough for play).
    10. The continuous 10,000 unit is reset to the zero position. This is done using a negative one position switch on the 100,000 unit, a switch on the ball release tray solenoid activator arm, and score motor switch 1A (the score motor will not stop until the 10,000 unit is at zero). Note the 10,000 unit relay is not used for resetting the 10,000 unit.
    11. The Points and 100,000 units are moved from the negative one to the zero position. This is done using the 100,000 relay (which increments the 100,000 unit) and a Points unit negative one position switch, which increments the Points unit using the 100,000 relay. The 100,000 relay is energized by the 10,000 unit being in the reset position and a negative one switch on the Points unit, and score motor switch 1A, and a switch on the ball release tray solenoid activator arm.
    12. Game is ready to play.
    13. As soon as the 10,000 point relay is scored once or twice, the ball release tray solenoid will de-energize allowing drained balls to be trapped.

      1954 Gottlieb "Double" Games.
      Double games allowed the player to put in an additional coin at the game start to double the number of any replays won. When one coin is inserted, the "thimble" light (on the lower ball arch) is lit, telling the player he can add another coin for a "double" game. This light stays on until the 10,000 unit is moved, turning off the ability for the player to add a coin for a "double" game. If a second coin was added, this will also turn the thimble light out, and the "double" light on the backglass goes on. Note the credit unit on a double game is slightly different than a conventional 1950s Gottlieb woodrail. It has an additional coil and mech that increments the credit unit two credits, instead of just one.

    1960s & 1970s Gottlieb Start-Up Sequence.
    Games with score reels.

    1. Inserting a coin or pressing the coin door start button (Gottlieb calls this the "replay" button) activates the "S" (start) relay. The start relay will lock on from its own switch and a score motor switch.
    2. The "S" relay will energize the main hold relay to illuminate the game (if this is the first game after power-on).
    3. The "S" relay will start the score motor running.
    4. The "S" relay and the score motor increment the total play meter.
    5. The "SB" relay (the secondary start relay) is activated through the score motor. The "SB" relay energizes the reset relays ("Z1" and "Z2"). If a single or two player game, there may be only a "Z" relay.
    6. The "Z2" relay will reset the player 3 and 4 score reels to zero through the score relays (4 player games only). The "Z1" or "Z" relay will reset the player 1 (and player 2 if present) score reels to zero through the score relays.
    7. The "SB" relay resets the player unit through the score motor.
    8. The "U" relay resets the reset bank (or Ax, Bx, relays on 1975 and later multi-player games and Ax on single players) through the score motor. It also resets the bonus unit or drop target banks (if the game has these).
    9. On multi-player games, inserting more coins or pressing the coin door start button activates the "PBx" relay, through the score motor. The "x" represents the player number (from two to four).
    10. If the ball is in the outhole, the "O" relay activates. The "O" relay, through the score motor and a switch on relay "XB", will kick the ball to the shooter lane. Note: the "O" relay will not activate unless the bonus unit (if the game has one) is reset to zero (there is a bonus unit zero position switch).
    11. When the ball re-enters the outhole after game play, the "P" relay kicks the ball back to the shooter lane. Switches on the "XB", "ZB", "P" relays and some score motor switches advances the player unit (if present) and player relays ("PBx").

    1975-1978 Gottlieb Start-Up Sequence.
    Multi-player games with Ax/Bx relays.

    1. Inserting a coin or pressing the coin door start button (Gottlieb calls this the "replay" button) activates the "S" (start) relay. The start relay will lock on from its own switch and a score motor switch.
    2. The "S" relay will start the score motor running.
    3. The "S" relay and the score motor increment the total play meter.
    4. On a 4 player game, the coin unit (next to the chime box) will decrement four times to the home (zero) position, and then kick up one position (to the 1 player position). Note if players 1 & 4 are lit on the backglass, the coin unit is not stepping up from the zero to one player position.
    5. The "S" relay energizes the Ax relay through the Bx (Last Ball) relay (sometimes), but always thru a switch on the "S" relay, "U" relay, and score motor switch at 2C. This should energize the Ax relay.
    6. The "R" hold relay pulls in and stays in, this turns off power to the Game Over relay (which stays energized when a game is finished).
    7. *On a 4-player game, the Player Unit in the backbox increments until it reaches the Z1 position. The Player Unit stops and the Z1 relay in the backbox energizes. The score motor resets the player 1&2 score reels through the Z1 relay. When all eight score reels are at "zero", the Z1 relay de-energizes and a normally closed switch on Z1 (very top switch, looks un-natural) allows the player control unit to increment to the Z2 position.
    8. *On a 4-player game, the Player Unit stops and the Z2 relay in the backbox energizes. The score motor resets the player 3&4 score reels through the Z2 relay. When all eight score reels are at "zero", the Z2 relay de-energizes and a normally closed switch on Z2 (very top switch, looks un-natural) allows the player control unit to increment to the "home" position (this is the "player 1, ball 1" position). (On a 4-player game there is a player unit switch stack for each player. This controls which set of score reels will score in the game.)
    9. *On a 2-player game there are no Z1 and Z2 relays. Instead the player unit uses two switch stacks (which would be the player3 and player4 stacks) and the score motor to reset all the score reels, instead of the Z1/Z2 relays and the score motor.
    10. Player unit is now at the "home" position ("player 1, ball 1" position). This is the P5A and P5B switches on the player unit, which is the switch stack closest to the backglass with only 2 switches. This causes the Ax relay to reset and the bonus unit to reset (if the game has a bonus unit). Often the P5A and P5B switches are dirty/mis-adjusted which will not let the score motor stop running.
    11. If the ball is in the outhole, the "O" relay activates kicking the ball to the shooter lane. Note: the "O" relay will not activate unless the bonus unit (if the game has one) is reset to zero (there is a bonus unit zero position switch).
    12. The ball passes over a trough switch as it is kicked from the outhole, which de-energized the "first ball" relay. Now the game will score. If this switch is closed after the "first ball" relay is de-energized, it will advance the player unit.

    Otis posted a nice Gottlieb start-up sequence for 1975 and later Gottlieb 4-player games. (This is another look at the same sequence as above.)

    1. Pressing the replay button with replays up will actuate "V" relay (replay button relay).
    2. "V" relay locks in thru a motor 2B switch and will actuate "S" relay.
    3. "S" relay will lock-in through its own switch and a motor 2B switch. "S" relay starts the motor running.
    4. "AX" relay actuates and the "coin" unit subtracts through switches on motor 3C, "S", and "AX" relays and a switch on motor 1A.
    5. "Q" relay de-energizes when "AX" relay operates. When "AX" relay actuates, the reset relays "Z1" and "Z2" are energized in sequence by rivets on the "Player" unit, through switches on "AX" relay.
    6. Motor 1A steps the "Player" unit, through switches on "AX" relay and "P5B", to the 20th position energizing "Z1". When "Z1" is energized the 1st and 2nd player score units reset to zero through switches on motor 1A, motor 4A and "Z1".
    7. When all the score units of the 1st and 2nd player are at zero, the player unit steps to the 21st position through a normally closed switch on "Z2" and normally closed switches on all score units of the 1st and 2nd players, actuating "Z2" relay. The 3rd and 4th player score units now reset through switches on motor 1A, motor 4A and "Z2".
    8. The player unit continues to its zero position through the closed switches on "Z1", "Z2", "P5B" and motor 1A until "P5B" opens. When "P5B" on the player unit closes, "AX" and "BX" relays reset through motor 4C and switches on "U" and "R" relays. The reset cycle is now complete.

    Williams Start-Up Sequence.

    1. When the start button is pressed, the credit unit is decremented. This is done through the credit unit zero position switch and the 2nd coin relay (and the ball count zero position switch).
    2. The end of stroke (EOS) switch on the credit unit decrement coil will energize the coin relay.
    3. The coin relay will trip the game over relay.
    4. The coin relay will energize the reset relay. The score motor will run.
    5. The reset relay will energize the ball count unit reset, through the score motor.
    6. The reset relay energizes the 2nd coin relay latch and game over relay latch coils.
    7. The reset relay will energize the score reset relays, through the score motor.
    8. The score reel reset relays will zero the score reels, through the score motor. The score motor will continue to activate the score reset relays until all the score reels reach the zero position.
    9. The reset relay activates the bonus unit coil until the bonus unit zero position switch is activated.
    10. When the bonus relay drops out, the outhole relay is energized through a different bonus unit zero switch and score motor switch.
    11. The outhole relay will run the score motor. The bonus unit will step up once. The ball will be kicked to the shooter lane.

    Following these sequences step by step, you can usually generally locate the start up sequence problem. For example, say you have a Gottlieb multi-player game. After pressing the start button, the score motor starts turning, and the score reels all move the zero position. But the score motor keeps spinning and nothing more happens. Looking at the start-up sequence, we can see this would probably be a problem with the "SB" relay and the player unit (or maybe a dirty score reel zero position switch, which occurs in the previous step).

3h. When Thing Still Don't Work: Reading Schematics
    Reading EM schematics is an art. It takes practice. But being able to do it well increases your chance of fixing a game completely. I'll be using Gottlieb schematics for this example. They are the hardest to read (in my opinion). So if you can figure out a Gottlieb EM schematic, you can read any EM schematic!

    First, before starting, note there is a BIG difference between a "schematic" and a "wiring diagram". A wiring diagram shows how the wires run through the game. A schematic shows how switches, relays, etc. are connected LOGICALLY to each other. Two parts that are logically connected on a schematic may not have a wire running directly between them! This can be confusing at times when tracing switches.

    How are the Schematics Drawn?
    There's a fair amount of confusion about this. My understanding is that schematics are drawn with the game reset (all score reels at zero), ready to play, for one player at first ball, and the game's power is turned off. If you're confused about whether the schematics are drawn with the power on or off, just look at the Hold relay's switches - this relay is energized when the game is on, so if the schematic were drawn with the game "on", then these Hold relay switches would be triggered. Note on Gottlieb games the schematics are also drawn with zero credits on the credit wheel (Williams and Bally schematics seem to be drawn with credits on the wheel.)

A Gottlieb schematic showing relay and coil usage.

    Relay, Control Bank, Other Coils Matrix.
    First lets look at the "relays", "control bank", and "other coils used" matrix on the left side of a Gottlieb schematic. This lists all the relays and solenoids used in a game. It provides some other cryptic information too.

    "INDEX" is the index reference. Notice the numbers down the left side of the schematic, and the letter across the top and bottom? These are the index. This makes it (fairly) easy to find where a particular coil or relay is written on a schematic.

    "NO." is the letter abbreviation for any coil or relay used. Most Gottlieb relays will have a sticker on them with this letter. This helps you find the coil or relay inside the game. This abbreviation is also used within the schematic itself.

    "COIL" is the coil number used for the relay. If you need to order a new relay, this is its part number.

    "TYPE" is the type of relay. "INTERLOCK" is a hold relay. "AG" is another style of relay used.

    "CONTACTS" tells the number and type of contact switches used on the relay. "4A,1B,2C" means this relay has 4 normally open switches (form A), 1 normally closed switch (form B), and 2 make/break switches (form C). The letters following the numbers are known as "forms". Form A is normally open, Form B is normally closed, and Form C is make/break. The number before the form is the number of this type of switch form used in the relay.

    "USE" is the verbal description of the relay.

    Schematic Markings.
    A Normally Open (NO) switch is two vertical parallel lines on the schematics. A Normally Closed (NC) switch is two vertical parallel lines with a diagonal line across them. A Make/Break switch is a NO and NC switch next to each other with an arrow line pointing to them both. The curly pig tail marking is a coil or relay. A short curly pig tail with a circle around it is a light bulb. Sometimes Williams and Bally uses a circle around a dot to indicate a score motor contact. Other weird markings are usually labeled.

Gottlieb Schematic Markings: most manufacturers use approximately
the same marking for their schematics too.

    Williams Schematic Abbreviations.
    Williams used some unusual abbreviations on their schematics, especially during the 1950s:
    • C = Closed
    • M = Motor
    • V = Volts
    • AMP = Amperes
    • CWE = Closed when Energized
    • CWI = Closed when In
    • CWP = Closed when Pushed
    • OWE = Open when Energized
    • OWI = Open when In
    • INT = Intermediate
    • SW = Switch
    • RE = Relay
    • NOV = Novelty
    • RP = Replay
    • RO = Roll Over
    • CON = Continuity

    Wire Color.
    Another matrix on the EM schematic is wire color. Each manufacturer has their own abbreviations for wire color (to keep it interesting). Check the schematics for this chart. Notice the schematic wires have this label (though some times you have to follow a wire back far through the schematic to its originating point to find the color marking). Some manufacturers use letters for colors, and some use numbers.

    Gottlieb uses the "-" and "&" markings between wire colors to mean different things. For example, "BL-WH" means a blue wire with a trace (small) amount of white. But "BL&WH" means a blue and white mottled wire, where each wire is 50% each color.

    Bally sometimes uses numbers after their wire color abbreviation. This is the number of times the same wire color has been previously used in the game! This keeps things interesting.

    Especially on Gottlieb games, the color red on the wires often fades to white. This makes a white and red wire look all white! This is very common.

    When a wire contacts a load (such as a lamp or a solenoid), the wire color will change. Wires that go through connectors should maintain their color(s). The connectors are very seldom shown on the schematics.

    Also note wire colors on the schematics can be wrong. It doesn't happen a lot, but it does happen.

Gottlieb's drawing of the Score Motor:
it's a VERY deceptive drawing. Note the "side"
view is devoid of all switches. The switches bolt
to the metal frame with all the holes, and run at
right angles to what the diagram seems to imply.

    The Schematic's Score Motor.
    How Gottlieb refers to the score motor is quite interesting and confusing. They give a diagram which shown the top and side views of the score motor, and labels each level or section.

    The top view shows each stack of switches is numbered, one to four. Note the angled switch stack, right next to the "cutout" at postion 3 1/2. This is a point of reference. Most score motors have number stickers on them to avoid confusion, but many times these sticker have fallen off.

    The side view shows the level letter of each stack of switches. The level closest to the bottom of the game is "A", and the top most is level "E". For example:

    • A = switches below the cam
    • B = switches activated with pins below the cam
    • C = switches activated by the cam itself
    • D = switches activated with pins above the cam
    • E = switches activated with TALL pins above the cam

    Armed with this info, you can figure out where a schematic switch is located on the score motor. For example, say you are looking for the switch that is labeled "Motor 1C". This would mean you look for the "1" stack of switches, the middle-most "C" level. If you examine this switch stack you might see four switches! Which one is it? This has to be determined by the wire colors, which should also be labeled on the schematics.

A Genco schematic (1954 Two Player Basketball). Notice the numbers next to the
switches. These numbers refer to the relay or unit the switch is mounted. For
example, a switch with "23" next to it indicates this switch is on relay 23 ("home
center trip" relay). The larger number ("1515") refers to a unit. The number under
the "1515" is the actual switch number and unit layer ("1B"). In this example,
there is a top and bottom ("T" and "B") layer to the 1515 unit. So the "1515/1B"
indicates the unit, the switch, and the layer of the unit.

3i. When Things Still Don't Work: Reading Schematics (part two) and Fixing Game Features

    This section is a continuation of the previous section entitled, "Reading Schematics."

    Often a particular game feature just won't work properly on an EM pinball. These can be frustrating to fix, especially when the rest of the game works perfectly. We will going through an example, and using the same schematics that were pictured in the previous section on reading schematics.

    Remember when looking at schematics, that they lay them out with some general electrical path in mind. In Gottlieb's case, this means the left side BLK wire goes to the right side RED-WH wire. Just keep that in mind.

    Helpful Hint: Using Feature Lamps to find Schematic Parts.
    An easy way to find out what controls a playfield feature is to find the lamp(s) associated with that feature on the schematics. Once the lamp(s) are found, you can trace them backwards to the relay that controls them. For example, say the "special when lit" feature is not working on your game. Find this lamp on the schematic, and trace the wires back to the relay that controls it. Now check and clean the switches on that relay and your problem may be fixed.

    Helpful Hint: Using Alligator Jumper Wires.
    Another helpful hint is to use those alligator clip jumper wires to bypass elements when trouble shooting. For example, if there are two switches going to a non-working coil, use the alligator clip jumper wires to bypass one switch. If the coil now works, this shows the problem lies somewhere in the bypassed switch area. If there are a number of switches, start "furthest" away, and bypass all the "in-between" switches. If the coil works, move the jumper one switch closer to the coil. Repeat until the coil no longer works. Using this technique the area that has the problem is made smaller, and easier to examine and find the problem.

Gottlieb's "Batter Up" EM Pinball Schematic: this section of the schematic deals with the "Home Run" game feature.

    An Example.
    Let's say the rollover switch on the playfield for the "Home Run" doesn't work. The switch itself is fine; clean and adjusted properly. But what ever it controls is not working.

    Looking at the "RELAY" matrix on the schematic, we can see there is a relay that controls the Home Run feature. It's abbreviated as "H", and is located at index 6E. Going to this part of the schematic, we see a relay coil labeled "H" with a WH-BL wire connecting to it. This is the Home Run relay coil. If you follow the wire to the right, notice it hits the "Home Run Rollover Switch", two normally open switches. These are the playfield mounted switches. The wire then continues down and to the right through "Motor 1C".

    At this point you need to check the score motor switch 1C and clean and adjust it. After that is done, test the feature. If it works, you're done. If not, you need to see what other paths exist for this feature.

    Notice just to the right of coil "H", the WH-BL wire goes down to a normally open switch labeled "H". This switch is on the H relay. Following it further down it continues to the right and eventually hits a normally closed switch through a WH wire labeled "Motor 2B". I would clean and adjust the WH-BL wire switch on the H relay, and clean and adjust the WH wire switch on the score motor at 2B.

    There's yet a third path that the Home Run feature takes: through the Vari-target. So if the feature still doesn't work, I would clean all the contacts on the Vari-target, and the OR-WH switch that goes to relay "U" (vari-target reset relay). After the U relay the wire terminates thru the NC motor 2B switch, which we previously cleaned and adjusted.

    Another Example.
    Here's another (trickier) example of using schematics. This time, when pressing the start button on a Bally Nip-it, the game would not reset properly. The "ball in play" display on the backglass would stay at ball 3. The stepper unit was recently rebuilt, so there were no mechanical issues. If I manually pressed the ball count unit reset coil, the stepper unit would reset, and the backglass would correctly state the first ball as "ball 1".

Bally's Nip-it: Note the "Ball Count Unit Reset Solenoid", top center.

    Looking at the schematic's "Ball Count Unit Reset Solenoid", I could see there were several other things getting reset through the same set of switches. Note the make/break Reset Relay switch, to the left. And just before that, was the Total Play Meter and Coin Unit Step Up coil. And controlling them was a switch on the Score Motor (3A), and a switch on the Coin Relay. Going in the other direction (to the right) effected the Player Unit only, and didn't seem to have anything to do with the reset sequence.

    I also noted that when I pressed the start button, the Total Play meter did not advance. This ruled out the make/break switch on the Reset Relay. Only thing left was the score motor switch 3A, and the coil relay switch. I examined both switch and they were clean and adjusted correctly. So what was causing the problem?

    If I looked closely at the Ball Count Unit Reset coil, I could see it was trying to reset when the start button was pushed. The pulse to reset this coil just wasn't long enough to pull the coil in and reset the stepper unit. Going back at the coin relay switch, I used a wire with two alligator clips and made the coin relay switch permanently closed. Hitting the start button now allowed the Ball Count Unit Reset coil enough time to reset properly!

    Since the coin relay switch was on the Coin Relay, what ever was controlling the Coin Relay wasn't keeping this relay energized long enough. Back to the schematics to look at what controls the Coin Relay!

Bally's Nip-it: Note the "Coin Relay", upper left corner.

    The Coin Relay is controlled by two parallel switches: one on the Coin Relay itself, and a switch on the Credit Relay. Then these go to the score motor switches 8F SCM and 10F SCM.

    First I looked at the two score motor switches (8F & 10F SCM). These were clean and adjusted properly. Next I checked the switch on the Coin Relay itself. This was a "hold" switch, and was clean and adjusted. That only left the Credit Relay switch. Hitting the start button while watching this switch, I could see the switch arcing. This was the problem! The switch was dirty enough and mis-adjusted enough to not make good contact. Adjusting and cleaning this switch fixed the problem.

3j. When Things Still Don't Work: Other Problems/Stories
Here's some other problems I've come across that may be interesting to a beginner EM fixer.

  • Problem: On a Bally EM, the general illumination (GI) dims during game play.
    Solution: Check the fuse holders. Particularly on Bally games, the fuse holders can lose their tension, causing the fuse to be loose. This can cause dim GI. The only solution on Bally's is to replace the fuse holder. Most other brands you can re-tension the fuse holder. In a pinch, you can use an aligator clip over the fuse and fuse holder saddles to keep the fuse in place, and provide proper tension and conductivity to the fuse holder.

  • Problem: On a Gottlieb EM, the Pop Bumper relay is stuck on. This in turn causes the score reel to be stuck on.
    Solution: To understand what was wrong, we have to know how the pop bumper works. When the ball on the playfield hits the pop bumper, it closes a switch which in turn, energizes the pop bumper relay. Then the relay does the following by closing it's normally open switches:
    • Closes a switch which keeps the pop bumper relay energized.
    • Energizes the associated score relay (to score the points).
    • Energizes the 00-90 unit (to advance the match and ring a bell), or activates just the bell solenoid.
    • Energizes the pop bumper coil itself to kick the ball.
    When the pop bumper coil itself is energized, the mechanism pulls in the coil plunger on the bumper. At the end of stroke (EOS) of the plunger, there is a normally closed EOS switch. When this switch opens, it interrupts the power to the pop bumper relay, which releases the relay.

    The solution is to clean and check two switches. First, clean and check the pop bumper coil EOS switch. If this fails, the pop bumper relay will forever stay energized because the power to it never gets interrupted. Second, there is a large set of contacts on the pop bumper relay, which controls power to the pop bumper coil. It turns out this contact was dirty and gapped to large. Hence the pop bumper relay would pull in, but not energize the pop bumper coil itself. Since the pop bumper coil never got energized, it never pulled the plunger in and never opened the EOS switch. Without opening the EOS switch, the power was never interrupted to the pop bumper relay. Cleaning and adjusting this switch fixed the problem.

  • Problem: On a Gottlieb EM, when a coil is energized, the lights dim on the game.
    Solution: When a coil fires (such as the pop bumpers), this significant power drain can dim the playfield lights slightly. If this happens more than "a little", the cause could be this: the Tilt relay!

    When a game is tilted, the tilt relay pulls in and turns off the power to the playfield lights and solenoids. If the tilt switches do not have good contact or good switch tension, playing the game can cause the tilt switches to open very slightly as the game vibrates. This can cause the game's lights to dim when a pop bumper is activated during play.

    To fix this, make sure all the switches on the tilt relay are clean, and making good contact. Also make sure the switch blades have ample spring tension, keeping their switch contacts tight when the relay is not energized.

  • On my Williams Magic City, the ball wouldn't kick out of the outhole strongly. It would usually just roll halfway up, then roll back and be kicked again.

    Solution: What I thought was a problem with the outhole kicker solenoid turned out instead to be a misadjusted switch on the score motor. This mis-adjusted score motor switch caused the solenoid to be activated not long enough to give the ball a good kick.

3k. Gottlieb Coin Doors and Flipper Buttons: the Shocking Truth
    You have your favorite Gottlieb game up and running (well almost). You're proud of yourself. So you decide to play a game. But you touch the start button on the coin door and ZAP! You get a nice friendly shock!

The fish paper that touches the start
(replay) button on this game has shifted
over (and may be torn). This allows the
metal start button to make direct contact
with the switch blades. SHOCKER!

    The reason this happens is because the metal start (replay) button is connected directly to the start relay. This relay operated on 115 volts, not 25 volts, like most other relays and coils. Since the start button is metal, Gottlieb puts a fish paper insulator between the button and the switch contacts. This prevents a shock. But with time the fish paper wears, tears, or shifts to the side. This allows the metal start button to touch the switch contacts directly. When you press the button, you become electricity's easiest path to ground. Hence you get a shock.

    Another way to get a shock is from the coin door coin switches. Again, at least one of these switches are connected directly to the start relay. If the fish paper that insulates these gets worn, torn or shifts to the side, again you'll get a shock.

Notice the fish paper on this coin door coin switch is ABOVE the
lever that trips the switch. This could cause a coin door shock. The
fish paper should be between the trip lever and the contact blade,
insulating the contact blade from the trip wire (which is metal and
touches the metal coin door).

    To make sure you don't get a shock, it's a good idea to replace the fish paper on the start button, and to check the fish paper on the coin switches.

Install a new power cord: cut the old power cord out of the game.
Wire a new one in (see black wires), and attach the green ground
wire to the metal frame of the transformer. Shown here is the brown
line cord which goes to a power switch at the front of the game.
When done, use nylon wire ties to attach the new power cord to the
existing wiring harness (like the old one was attached). The "hot"
(black) wire of the new power cord should route to the game's
fuse/power switch. It won't mess anything up if it's backwards, but
for safety reasons it's better if black goes to the power switch.
If there is a rib on the old power cord's insulation, this is
the neutral line. Also the "thin blade" of the prong is hot.

    Installing a New Power Cord.
    I always replace the power cord on any EM game I fix up. The originals are usually worn, or the insulation is cracking. You can replace the original two prong cord with another two prong power cord - just go to the local Dollar store and buy a 15 foot two prong extension cord for $2. Cut off the recepticle end of the cord, and you have a new power cord for a nice low price. Note the new power cord should have one line with "ribs" in the rubber insulator. This is the white or "neutral" line. The "hot" (black) wire is the new power cord's "smooth" line (which connects to the narrow power prong.) The hot line should connect to the game's power switch (if the game has one) and fuse.

    For better safety, it's not a bad idea to replace the game's original two prong power cord with a grounded three prong cord. Again, the same technique can be used - buy an inexpensive three prong 15 foot extension cord at the Dollar store and cut off the recepticle end. Also again the new power cord should have a "ribbed" insulator wire which connects to the larger of the two power prongs. This is the "neutral" (white) wire. The "hot" (black or smooth wire or narrow prong) should connect to the line going to the power switch. The green ground wire should connect to the transformer's metal frame bolt. Optionally, additional grounds can then be run from the transformer's metal frame to other metal objects (like the lockdown bar and metal side rails and metal leg plates).

    Flipper Button Shocks.
    Just like the coin door button, flipper buttons can often give a nice shock too. This usually happens if touching both flipper buttons. Gottlieb used metal flipper buttons from 1960 (wedgehead cabinets) all the way into the 1970s, so this problem is fairly common. Again just like the coin door replay button, there is fish paper which insulates the the metal activator from the flipper switches (which are 30 volts). If the fish paper wears or breaks, the player can get a shock from the flipper buttons. Replace the fish paper (or use electrical tape) and the problem should go away.

    Grounding the Game.
    Another good idea is to ground your game. Installing a NEW three prong power cord and plug is a good idea. The original power cord is probably 25+ years old. Remember the black power cord line is "hot", and should run to the game's power switch. On the old power cord often there is a "rib" on the wire which denotes the black (hot) power line. Run the power cord's ground wire to the metal frame of the power transformer. Then run a wire from the transformer's frame to the back end of the metal side rails. Run another wire from the front end of the side rail to the coin door and lock down bar. Lastly, run a wire from the coin door to the other side rail. While you're at it, it may not be a bad idea to add a power switch to your game too (as discussed previously in the Typically What's Wrong section).

3L. Coils Explained: Coil Power and Size, Testing Coils, Low Resistance Coils, Big Blue Sparks, Rewinding Coils, Coil Equivalents.

    Coil Voltage.
    Most EM game makers used 24 to 30 volts AC for coil voltage. One exception was Bally during the 1970s (50 volts), and Williams. Williams used 50 volts AC for coil voltage until 1962 (Friendship7), when Williams changed to 24 volts AC. The reason? Fifty volts is potentially lethal, so Williams felt it was better to use a lower voltage. Also using a lower voltage meant using less copper wire for coils, so there was a cost savings too. The down side to a lower coil voltage is there's less ability to really tune coils to the exact power needed (this is why Williams went back to 50 volts for coil voltage in the 1980s). Also 50 volt games tend to be a bit more 'peppy'.

    Coil ohms vary dramatically between 25 and 50 volt games. For example, Gottlieb used 25 volts and their pop bumper coil ohms are around 3 ohms. Bally used 50 volts and their pop bumper coil ohms are around 10 ohms. Even though both coils look the same (same frame size), if you put a Gottlieb pop bumper coil in a Bally game it would be WAY too powerful. Likewise a Bally pop bumper coil in a Gottlieb game would be way under-powered.

    As a basic rule, increasing the coil wire gauge by two sizes will double the coil resistance per foot (making the coil less powerful). So if a 25 volt coil uses 20 gauge wire for a pop bumper, going to 22 gauge would be about right for a 50 volt application (given the same number of coil turns).

    Coils Power Explained.
    A coil's strength is basically determined by three things: the voltage to the coil, the number of turns of wire, and the gauge (thickness) of the wire. Since the voltage usually cannot be changed in a game (other than putting the game on "high tap"), only the number of turns and/or wire gauge can be changed. Here's what to remember:

    • The higher the voltage feed to the coil, the more powerful it will be.
    • The lower the resistance of a coil, the more powerful it will be.*
    • The less turns of wire, the lower the resistance, and the more powerful the coil.*
    • The thicker the gauge of the wire, the less resistance, and the more powerful the coil.*
    • * If coil resistance is too low (about 2 ohms or less), a coil stops having magnetic strength and starts becoming a dead short.

    The "less turns of wire, the more powerful it will be" rule is only good up to a point. That is, if the resistance of a coil goes below about 2.0 ohms, it becomes essentially a dead short. This means the coil will not work correctly, and may blow fuses too. Also a coil with too little wire (or shorted wire) can have an inadequate magnetic field.

    With this in mind, if at least one lug of the coil can be desoldered from its attaching wire, the coil's resistance can be measured using a DMM (Digital Multi-Meter). If the coil is measured with the DMM "in circuit", an accurate reading may not be seen unless one lug of the coil is freed from its connecting wire. This isn't the rule, it just depends on the coil being tested. Remember electricity takes the path of least resistance. So if the coil being tested is a pop bumper coil (a low resistance coil), there should be no problem testing it in-circuit. If the coil is a hold relay (higher resistance), it may not test well in-circuit because there are other lower resistance coils in that circuit.

    Coils range in resistance from about 2.0 ohms up to 150 ohms (the lowest resistance coil I have ever encountered is on Williams' 1965 Mini Golf, which uses a 21-475, 1.8 ohm coil, but this is the exception not the rule - also the Gottlieb A-5141 flipper coils have 1.9 ohm resistance on the power side). The higher the resistance, the less powerful the coil will be. But on the other hand, high resistance coils can stay energized for a long time without getting hot and burning! That's why "hold" relays, which stay energized for periods of time, use high resistance coils (usually 30 ohms or higher).

    Remember flipper coils are actually two coils in one package. There is a low resistance (usually 3 ohms or so), high power initial flip coil. And there is a high resistance (usually around 125 ohms), low power "hold" coil. The high power side is activated initially, to kick the ball hard. The hold coil is then placed in series with the power coil (using the now open flipper EOS switch) to allow the player to hold the flipper button in, without burning the coil.

    Coil Frame Size.
    The nylon frame is what the coil wire is wound around. As a general rule, Gottlieb and Bally used a 1 1/2" coil frame (with a 1 5/8" long coil sleeve). Williams used 1 5/8" coil frame (with a 1 3/4" coil sleeve). This is good to know if you are trying to use a coil from a different manufacturer in a particular game. That is, Williams coils won't physically fit well in Gottlieb or Bally games, and vice versa.

    The Big Blue Spark.
    If the playfield is raised on an EM pinball and the lights are out, you can see a lot of "blue sparks" coming from the switches. This is normal to some degree. But none of the blue sparks should be "huge."

    The largest of the blue sparks can be seen at the flipper coil's EOS switch. No other switch in an EM game should have a blue spark as large as the flipper EOS switch. Remember the flipper coil is actually two coils in one package - a high current, high power, low resistance coil, and a low current, low power, high resistance coil. The EOS switch spark is the high current, high power part of the coil collapsing, and causing the blue spark. This happens because the flipper coil's high power side is often very low ohms (around 2 ohms often), and the flipper EOS switch is what turns off the high power side of the flipper coil.

    So Why the Big Blue Spark?
    The only reason a switch gives a big blue spark is if something is consuming masses of current. And the only way that happens is if there is a low ohm coil in the circuit. Low ohm coils are nearly a dead short (very low resistance), hence they consume lots of current.

    The blue spark is caused by EMF - Electro Motive Force. As any energized coil collapses, it back-spikes *twice* the game's voltage back through the switches. That means if a coil is energized at 25 volts, it will back-spike 50 volts. The lower the coil's resistance, the more EMF and the larger the back spike. Interestingly this is suppressed on Solidstate games with a diode on a coil (the back spike of EMF can ruin a CPU board). But since EM games are AC power and there's no CPU, manufacturers don't use diodes.

    Some switches in a game are prone to burning contacts due to EMF. The two big culprits are the flipper EOS switches and the score motor home switch. In the case of flipper EOS switches, as the high power part of the flipper coil collapses due to the EOS switch opening, it causes a large blue spark from the EMF. Again the size of this spark is due to the low-ohm nature of the high powered side of the flipper coil.

    On the score motor home switch the large blue spark is caused when the score motor's home switch (the switch on the score motor that keeps the motor running through a half or third of a revolution) *opens*, turning the motor *off*. Interestingly, if you look at the home switch when it closes the spark is really small or non-existent. But when the switch opens, turning off the score motor, the blue spark is huge! Again this is due to the score motor's coil EMF collapsing and back-flowing twice the score motor voltage through the home switch. If you measure the resistance of the score motor it is often around 2 ohms, hence the EMF when the motor turns off will create the big blue spark.

    A big blue spark can also happen on stepper units. Remember a stepper unit is merely a big stack of switches. As the fingers move from stepper pad to stepper pad, a "switch" opens as the stepper fingers move off a copper pad. If a stepper unit's bakelite pad is burning, there is most likely a low-ohm coil in that circuit causing the big blue spark and burning the bakelite copper pad. This happens as the stepper's fingers move *off* the burnt pad (and a low-ohm coil collapses causing back flowing EMF to burn the pad and cause a big blue spark). Note Gottlieb sometimes used a 8200 ohm resistor (or other value) on stepper units or coils, in the path of a coil. This helped reduce the blue spark from EMF.

    How do Coils go Bad?
    So how do coils go 'bad'? If they get hot, the wire's enamel painted insulation will burn, allowing adjacent turns of the wire to short against each other. This can greatly reduce the resistance of the coil, making it unusable. Shorted coil windings (even if the total resistance is not less than 2 ohms) also messes up the magnetic field of the coil.

    I like to keep a list of common coil numbers and their resistance. This way I can check a questionable coil with my ohm meter, compare the coil's ohms it to my list, and determine if the coil is good or bad. Or if the coil is not on my list, if the game uses the same coil else where, I can compare the two coils' resistance.

Here's a coil that is "cooked". Notice the broken wire in the windings. This coil
will measure "open" on the DMM. Note not all bad coils will be this obvious. The
best way to identify a bad coil is to test it with a DMM set to resistance.
Anything under 2 ohms is a bad coil.

    Testing Game Coils to Prevent Blown Fuses.
    A very good idea for any unknown game just purchased is to check all the coils' resistance. If the game is new to you, and you have not powered it on, a quick check of coil resistance will tell you a lot about your new game. This takes about one minute and can save you hours of repair and diagnosing work. It can also save you countless fuses!

    Any coil that has locked on will heat up and have a lower total resistance. This happens because the painted enamel insulation on the coil's wire burns, causing the windings to short against each other. This will lower the coil's resistance, causing the coil to get even hotter. Within a minute or so the coil becomes a dead short, and usually blows a fuse. If the fuse is replaced, it will just blown again and again until the low resistance coil is replaced.

    In order to check coil resistance, put your DMM on its lowest resistance setting. Then put the DMM's red and black leads on each coil's lugs. The coils can usually be checked right in the game without having to disconnect any wires. A resistance of 2 ohms or greater should be seen. Anything less than 2 ohms, and the coil is bad! Replace the coil with a new one.

    Coil Numbers.
    Coils often have the numbers AE-22-1200-1 or something similar. Here's what this means:

    • AE = The coil form size (the size of the coil's frame).
    • 22 = The wire gauge. The higher the number, the thinner the wire (and more resistance, and less powerful the coil). The lower the number, the thicker the wire (and less resistance, and more powerful the coil).
    • 1200 = Number of turns or wraps around of the wire around the coil. The less turns, the less resistance and stronger the coil.
    • -1 (optional) = This can denote the style of lugs on the coil, or the type of coil sleeve used in the coil for a particular application.

    Some manufactures (mainly Gottlieb), didn't use the above coil numbering system. Instead they just have a numbering system that don't relate to the coil's wiring (like A-5141 for their flipper coils). In this case, some people have documented the wire gauge, turns, and resistance of these coils.

    EM Flipper coils have a slightly different numbering system, since they are actually two coils in one package. These usually have a coil size letter, followed by two pairs of numbers.

The broken wire was reattached on this coil and checked with the
DMM. Note the resistance is only 1.0 ohms! This coil is *bad* and
must be replaced.

    Broken Coils.
    Coils can often have the wire winding break from the solder lug. This is often an easy fix. Just unwind a single "wrap" from of the wire (if possible), sand the wire clean to remove the painted enamel insulation, and then resolder the wound wire to the lug. Then test the coil with a DMM to make sure it is not open.

    A Low Resistance Coil Problem.
    Problem: "The ball release coil on my Gottlieb 1965 Central Park doesn't de-energize, and I see a BIG spark from the switch contacts on the ball release coil and on the one point relay."

    The ball release coil is a hold coil. It stays energized until the first ball scores a point. There is a normally closed switch on the one point relay. When a point is scored, this switch opens, and de-energizes the ball release coil.

    The key here is the "big spark" on the switches. This signifies that the coil has a resistance that is too low. This happens often on hold coils, which stay energized for a long time. These coils get hot, and burn their insulation from the internal wires with time. This causes an internal coil short, and lowers the coil's resistance. This in turn causes more heat, and more burning, until the coil is a near short (less than 3 ohms). Any hold coil should have a resistance of 12 ohms to 200 ohms. Less than 10 ohms, and the coil will get hot quickly and burn if energized for even short periods of time.

    When you get a "big spark" between switches, this mean electricity is arcing between the switch points. This doesn't allow a normally closed switch to really open, and the hold coil never de-energizes. Since the ball release coil's resistance was so low, this made the release switch arc, and never allowed the switch to open (and de-energize the coil).

    After the ball release coil was replaced, the excessive switch arcing stopped, and the coil worked as it should (it de-energized when the one point relay was activated).

    Rewinding a Coil.
    In some situations you may be stuck with a burnt up coil, and perhaps a new one cannot be found or bought. This can happen especially on 1950s EM arcade games and shuffle alleys that use coils that are a lot harder to find. Perhaps the old coil wire is burned, but the "frame" (the aluminum or brass sleeve and surrounding fiber parts) are still usable. If this is the case you can re-wind the old coil with new wire.

The original brass coil sleeve for a 1954 United Shuffle alley is shown below. The plunger wore right thru the brass and into the wire, causing a short in the coil. With the coil's sudden low resistance, the coil wire burned. Here I have removed the old wire from the sleeve, and slide off the old fiber frame pieces. I then transplanted the fiber pieces to a new aluminum coil sleeve, and rewound the coil.

    Assuming the old coil's frame is usable (this obviously won't work if the coil frame or sleeve is melted nylon!), remove all the old burnt wire from the coil. Usually this is just a matter of unwinding the burnt wire. Only takes a moment to do this. With the wire remove examine the coil sleeve. If there are no holes worn through, it can be reused.

    Go to the game's schematics and find the coil. Usually there is a key specifying the wire gauge and number of turns for the coil (exception is Gottlieb, see chart below). In the case of the shown United shuffle alley, the coil was marked on the schematics as 24-965 (24 gauge wire, 965 turns). Now it's just a matter of finding another donor coil with the same or near specs. Again in my case I used a Williams bumper coil (24-900). Not quite as many turns, but same gauge wire. The frame size was smaller on the Williams donor coil, so really it would have been better to get a 24-1100 coil (which would more closely match the 24-965), but in my case I only had the 24-900 coil. This isn't rocket science, so a close match will work fine.

    Another technique to finding a good donor coil is to match resistance. But the problem is you need to know the resistance of the original burnt coil. Perhaps that same coil number is used elsewhere in the game and is still good. Check its resistance with a digital multimeter. Now find a donor coil with the same (or close) wire gauge and a close resistance.

    After the donor coil is choosen, it's just a matter of turning the wire off the donor coil onto the empty coil frame. This is easy to do using a drill (see picture below). It is a two person operation though, as someone has to hold the donor coil on a screwdriver shaft with some slight tension, while another person runs the drill with the accepting coil frame. Just attach the wire to one lug of the empty coil frame, run the drill slowly and unwind the wire from the donor coil onto the empty coil frame. Only takes about 5 minutes to do an entire coil.

Winding the wire off the donor coil and onto the new coil frame using a drill. Go slow, but an entire coil can be rewound in about 5 minutes. Shown below is the empty donor coil frame (on the screwdriver), and the freshly wound coil (mounted on a bolt going into the drill chuck).

    Finally sand the ends of the newly transplanted wires (to remove the painted enamel insulation), and wrap/solder the wire to the lugs of the coil frame. Your newly rewind coil is now ready for use.

    Gottlieb Coil Usages and Coil Equivalents.
    This is not a complete list, but it does give some substitutes for Gottlieb coils. Use CTRL-F to easily find the coil number desired. Please keep in mind a few things. For example, new coils are wound on a nylon base where older coils may be wound on a fiber base. New coils always use a nylon sleeve, where old coils may use a brass sleeve. Also some new relay coils may have the coil lugs on the opposite end of the coil (which is fine, just mounts slightly different).

    As for part numbers, Gottlieb started all part numbers with A-1 in 1946. The "A" refers to the size of the paper on which the original mechanical drawing for the coil/relay/part was drawn. This way all the "A" sized paper went into the "A" sized filing cabinet. There are some exceptions to this rule, but for the most part that's what Gottlieb did (note "A" does *not* mean "assembly.") Gottlieb ended in 1996 with part numbers in the 33,000 range. Based on this, you can get a general idea of when a part was implemented into production based on the part number.

3m. Coils Explained: Coil Resistance/Substituion Info.

Gottlieb Relays and Coil Substitutes.
Coil Number Equivalents Type Ohms Usage
A-1119, C20-3 relay 2.1 Trip bank, in series with another relay
R20-1, A-9746 relay 1.5 in series with another relay
R20-2, A-7688, A-9733, A-487, #2 relay 2.0 Interlock, in series with another relay
R20-3, A-9742, A-7834, A-1084, #10 relay 10 Tilt
R20-4, A-9735, A-7676, A-7835, A-5662, A-3891, A-489, #15 relay 15 most common relay used for general use
R20-5, A-9736, A-7677, #25 relay 25 30v hold, Alt, Coin Lockout, 1st ball
R20-6, A-5294, A-3890 relay ~385 120 volt R (reset) & S (start) relays
A-9740, A-6698, A-7846 relay 22 Credit Hold, Game over hold, pop relay, vari-target
A-9738, A-7836, A-3498 relay 32 110v hold, 30v hold, Tilt Hold
A-6821, A-5457 relay   general
A-5141, A-1657, A-1546 solenoid 1.9, 6 Flipper
A-5193, A-3104 solenoid   reel drive
A-5195, A-1943, A-622, A-12092 solenoid 12 Chime, Ball release
A-5196, A-1318, A-9479, A-15555 solenoid   Bank step-up, Bank reset
A-1856 relay 275 start relay
A-9479, A-5196, A-1318, A-15555 solenoid   bank reset
A20-2, A-17875 (use high power winding) solenoid   Counter
A20-4, A-5197, A-7800, A-1640 solenoid   Bank reset, Bank SU, Roto, turret shooter
A20-6, A-5143, A-5194, A-940, A-1448, A-3537, A-2563 solenoid 3.6 Reset, Kicker, Bell, Knocker
A20-8, A-4893, A-939, A-2435 solenoid   Bell, Pops, Hole eject

Gottlieb Coil/Relay Information.
Gottlieb Coil Wire Gauge/Turns Ohms Wrapper Color Usage
A-1118 ? 3.6 black feature bank relay
A-1496 23-635 2.95 Yellow Pops, Slings, General Purpose
A-4893 22-535 2.1 Red Up kicker, pop bumpers
A-5141 ? 1.9/ 6 Green Flipper (EM)
A-5141 ydot ?1.0/ 6 Green w/ yellow dot Flipper High Power EM
A-5143 ? 3.6 Black 1960s Bell coil
A-5194 24-780 4.5 Blue Up kicker, Pop Bumpers, Slings
A-5195 26-1305 11.6 White Knocker, Outhole
A-7112 ? 155 red or black 120 volt start relay (1960s)
A-9736 ? 22 ? 1st ball relay (1975-1979)
A-9738 ? 32 ? tilt hold relay (1975-1979)
A-9740 ? 24 ? Game Over relay (1975-1979)
A-16570 27-1450 15.5 Green Ball release
A-16890 35-4000 231 Orange Q/T Relay sys1&80
A-16890 35-4000 225 Orange Q/T relays
A-17875 24-560/31-1100 2.8/40 Yellow Flippers s80
A-17876 28-1750 24 Tan General Purpose
A-17891 22-850 3.35 Red 5 bank reset
A-17891 22-850 3.35 White 5 Target Reset
A-18102 24-1430 9.0 Orange target bank reset (uses 2)
A-18318 24-1130 6.7 Orange 4 target bank reset
A-18642 33-1590 58 White Memory relay, target trip relay
A-19300 25-1075 7.8 Orange Ball kicker
A-19508 32-1250 35 Yellow Target Trip/Relay
A-20095 22-450/31-900 1.55/35.5 Red Flipper (strong)
A-20558 34-3400 156 White Gate relay
A-21741 23-575 2.5 Orange Vertical Up kicker
A-26450 29-2400 42 Pink General Purpose
A-26451 30-3000 65.8 Blue General Purpose
A-26452 35-2450 137 Pink Target Trip/Relay
A-26926 27-2650 32.8 Blue 3 Target Reset
A-27926 29-3475 64.7 Blue General Purpose
A-30297 30-2750 66.5 Blue General Purpose

Gottlieb Flipper Coils.
Gottlieb Coil Wire Gauge/Turns Ohms Wrapper Color Usage
A-5141 ? 1.9/ 6 Green Flipper (EM)
A-17875 24-560/ 31-1100 2.8/ 40 Yellow Flipper normal s80
A-24161 23-520/ 31-1050 2.2/ 40 Blue S Flipper medium
A-20095 22-450/ 31-900 1.55/ 35.5 Red Flipper strong
A-25959 22-445/ 30-1225 3.85/ 202 Red Flipper (new)
A-26646 25-725/ 33-3470 4.57/ 201 Blue Flipper (new)
A-27642 27-950/ 33-3700 9.1/ 203 Yellow Flipper (new)
A-27643 28-960/ 33-4700 11.59/ 269 White Flipper (old)
A-28740 26-790/ 33-3600 6.02/ 207 Tan Flipper (new)
A-29876 23-560/ 33-3325 2.36/ 202 Orange Flipper (new)
A-30468 28-960/ 33-4700 11.59/ 269 White Flipper (Old)
A-31272 30-2200/ 34-3575 44.8/ 268 Blue Flipper
Gottlieb Coil Wire Gauge/Turns Ohms Wrapper Color Usage

Wms/Bly Coil Wire Gauge/Turns Ohms Usage
ae23-800 26/1200 4 pop bumper
ae22-900 26/1200 6 pop bumper
ae26-1025 26/1025 9 chimes
ae26-1200 26/1200 11 slingshot
ae27-1200 27/1200 13 outhole
af25-600/28-800 ? 4.1/14.2 flipper
Aq25-500/34-4500 ? 3.3/30 flipper
A-20099 ? 30/195 Trap door TOM
FL-11753 ? 9.8/160 wpc small flipper
FL-11722 ? 6.2/160 wpc upper flipper
FL-11630 ? 4.7/160 std s11/wpc red flipper
FL-15411 ? 4.2/160 strong wpc org flipper
FL-11629 ? 4.0/160 strongest wpc blue flipper

Early Bally EM Wire Gauge/Turns Ohms Usage
KKN 3310 ? 88 relay
KKN 3311 ? ? relay
KKN 3312 33/2300 116 Anti-Cheat relay
KKN 3314 ? ? relay
KKN 3315 ? 18+100 dual wound 3 lug relay
KKN 3316 ? 18+70 dual wound 3 lug relay
KK 331 ? 85 relay
KK 334 ? 63 relay
G-28-750 28-750 9 relay
G-30-1500 30-1500 28 relay
G-31-1600 31-1600 35 relay
G-32-7500 32-7500 74 relay
G-32-2500 32-2500 mid-70s hold relay
G-32-1250 32-1250 45/30 dual wound 3 lug relay
G-32-2500 32-2500 74 relay
G-33-2800 33-2800 110 relay
G-35-5200 35-5200 160 relay
G-35-2200 35-2200 200 relay
G-35-2000 35-2000 100 relay
G-38-8000 38-8000 900 relay
EA-30-1550 30-1550 20 relay
EA-32-1550 32-1550 40 relay
FC-32-2100 32-2100 60 relay
FD-30-1150 30-1150 20 relay
FD-30-1300 30-1300 23 relay
FD-36-7000 36-7000 530 relay
K-31-2000 31-2000 48 relay
K-32-2150 32-2150 68 relay
K-33-600 33-600 68 relay
K-33-1650 33-1650 16 relay
K-33-2000 33-2000 68 relay
K-33-2300 33-2300 81 relay
M-37-2700 37-2700 115 relay

Williams Coil Wire Gauge/Turns Ohms Usage
z27-1000 27/1000 10 impulse relay
z28-1150 28/1150 14 impulse relay
z28-1200 28/1200 14.5 hold relay
z29-1250 27/1000 18 hold relay
z30-1800 30/1300 31 hold relay
m29-1100 29/1100 16.5 hold relay
m29-1750 29/1750 29 hold relay
m30-1300 30/1300 26 hold relay
m31-1500 31/1500 35 hold relay
a22-550 22/550 2.3 impulse coil
g23-750 23/750 4 impulse coil
g23-600 23/600 3 impulse coil
b26-800 26/800 3 impulse coil
a26-1300 26/1300 12 impulse coil

3n. Pop Bumpers.

    The Pop Bumper is one of the most common pinball features, as most games from WW2 to present have at least one pop bumper. When the ball hits the "bumper skirt" it pushes down on the skirt. There is a stem that extends down from the skirt and into the center of a concave tip on a leaf switch. Pushing down on one side of the skirt causes the stem to push down on the switch. The switch then energizes a pop bumper relay. The relay in turn usually does at least two things: energizes the pop bumper itself, and activates the one or ten or 100 point relay to score points (and ring a bell).

    If a pop bumper locks on (stays energized) after a ball hits it, usually the pop bumper relay is locked on also. The key to fixing this is often the end-of-stroke switch (aka scoring switch) on the pop bumper mechanism. On Gottlieb games, this switch opens as the pop bumper fully energizes. When this switch opens, the power circuit to the pop bumper relay is broken, de-energizing the relay. This in turn de-energizes the pop bumper itself (and the scoring reel and bell). If this pop bumper end of stroke switch is broken or missing, usually the pop bumper relay will stay energized once the ball hits a pop bumper skirt.

Pop bumper diagrams from Bally.

    Rebuilding EM Pinball Pop Bumpers
    Having quick and perky pop bumpers make any game a lot more fun. Chances are your game needs it anyway. Tell tale signs would include chipped bumper skirts (the bumper skirt is the plastic part the ball contacts on the bumper that tells the bumper to "pop") and lots of dirt.

    This procedure also applies to stationary bumpers. These bumpers look like pop bumpers, but don't "pop". The have no coil or rod & ring assembly.

The top of a pop bumper with the cap removed. Note
the two screws that hold the bumper body to the playfield.
Also note the wedge style light socket. This will be
replaced with a bayonet (#47) style socket. The top of
the metal ring of the rod & ring assembly is also visible.

    Removing or Repairing a Pop Bumper.
    From the top of the playfield, remove the bumper caps. Usually two small screws holds it in place (though some are press fit). Then remove the light bulb. You will see two screws that hold the bumper body to the playfield, next to the light socket. Remove these two screws.

Bottom of the playfield: This picture shows the lamp
socket leads and the rod nuts, and plunger/coil assembly.

    From the bottom of the playfield you need to remove the two locknuts from the rod & ring assembly. Then unsolder the two light socket leads underneath the playfield. On some games (including this one), there are staples that secure these leads, which you will have to remove. Now the bumper body and rod and ring can be removed from the top of the playfield.

    Also check the bakelite and metal armature links that slide inside the coil plunger, which the rod and ring assembly bolt to. These often crack or break and need replacement. The steel link breaks the most often. The older Gottlieb version is no longer available, but you can replace them with new Williams steel armature links, part number 01-5492. I do NOT recommend the Williams part though. They are not hardened steel (like the Gottlieb part), and often break. You can get a new style Gottlieb metal armature that is hardened. It is slightly bigger though. So you either have to grind it smaller, or modify your pop bumper bracket (see pictures below).

Left: Modified Gottlieb pop bumper brackets to accommodate the newer (bigger) Gottlieb metal armature plate. Note the sides are indented with a grinder.
Right: The top of this picture is a new Gottlieb metal armature link. These are hardened steel, and will not break. Below it is the cheap Williams metal armature link that is so soft, I can bend it with my fingers!

    Note when re-assemblying the armature plates, the bakelite spacer mounts closest to the rod & ring nuts, and the steel link contacts the metal bracket.

    Inspect the Rod and Ring.
    It is very important you inspect the rod and ring assembly for defects. If the rods are loose, replace the rod and ring assembly. If the threaded ends are not square to the rod, this is also cause for replacing the rod and ring.

    Tighten or Re-peen the coil stop.
    The coil stop on the pop bumper bracket should be tightened or re-peened (if it's a riveted coil stop).

    Check the pop bumper spring.
    The spring that goes over the pop bumper plunger is probably very tired. You should either replace this spring, or re-stretch it to the length of the pop bumper coil.

    Install a New pop bumper lamp socket.
    Don't even attempt to re-use the old lamp socket. Buy a new socket. The old socket is probably corroded anyway, and should be replaced.

    After removing the two screws inside the bumper body (and disconnecting the rod and ring and bumper lamp socket from under the playfield), lift the bumper body off the playfield. Note all the dirt and crude that lives under the bumper body! If you have clear plastic trim platter protectors, there will be lots more crud under those. Now is a good time to clean the playfield under the bumpers with Novus2. When finished with the Novus2, wax this area.

Left: Removing the pop bumper coil and replacing the coil sleeve.
Right: Note the metal armature link touches the metal bracket. Also note the two links' openings face each other, mounting from opposite sides.


    Pop Bumper Performance Tips:

    • While you're under the playfield, replace the pop bumper coil sleeve. Remove the two screws that hold the pop bumper coil to its bracket. The two screws hold the coil retainer in place. The old coil sleeve should just slide out. If it doesn't, the coil is heat damaged and should be replaced. Install a new coil sleeve. This will increase performance.
    • Polish the ring of the rod & ring assembly on your buffer. This will smooth the surface (which contacts the ball) and reduce friction. This makes the ball kick faster. A cheap and easy performance tip if you already have a buffer. If the rod & ring is damaged, bent or has loose rods, replace it. New rod & rings assemblies need the ring polished too, as they aren't that smooth.
    • Remove the bakelite and metal armature links from the coil plunger. Using "Goop" (available at most hardware stores), glue them together. Then "Goop" the bakelite and metal armature links to the pop bumper coil plunger. Remember, the bakelite spacer mounts closest to the rod & ring nuts and the plunger. Put the plunger in a vice to let the whole assembly dry overnight. This will remove any play between these devices.
    • While you're replacing the coil sleeve, you can also unwind three "layers" of coil winding wire from the pop bumper coil. This will lower the coil resistance, and make the bumper faster. See the following performance tips for a description of this. But basically, first remove the paper wrapping from the coil. Then cut the outside coil winding from the solder lug (don't cut the inside coil winding; you can't unwrap wire from the inside!). Unwrap three layers of wire. A layer is about 40 turns of wire. After the third layer is unwound, leave about two inches of wire and cut off the extra wire. Now sand the wire to remove the painted enamel insulation, and put it through the solder lug. Wrap the remainder around the solder lug. Replace the coil and solder the wire in place on the solder lug.

Lifting the pop bumper off the playfield.
Note the chipped bumper skirt.

    Trim Platters.
    Gottlieb games after 1965 have round mylar (clear plastic film) "trim platters" that protect the pop bumper area. Remove the mylar and clean the glue off the playfield with Goo Gone. Clean the playfield with Novus#2. At this point you can replace or add the clear trim platters, but I wouldn't unless there's excessive wear.

    Note trim platters come two ways: adhesive backed, and non-adhesive. I personally like the adhesive backed units. They don't shift or move, and dirt doesn't get under them. Also, the non-adhesive trim platters can actually contribute to pop bumper wear. As the ball skates across the platter, they shift slightly on the playfield. The shifting of the platter can cause wear, hence defeating their purpose.

The parts of a pop bumper. The picture on the left was taken before cleaning.
The picture next to it was taken after cleaning the body, replacing the skirt,
and polishing the ring. Use these pictures for reference when re-assembling.
Note the orientation of the bumper base in these photos; the two lamp lead holes
have extents. These extents do not line up on top of the bumper body's extents.


    Clean the bumper body with Novus#2. Replace if cracked or damaged (bumper bodies aren't expensive). Sometimes the bumper base will break off inside the bumper body when you are separating the parts. Replace as needed. Replace the bumper skirt. They are about one dollar brand new, and look better, even if the old ones aren't damaged. Also install a new light socket for the pop bumper. If your game had 555 wedge type bulbs (as this game does), get #47 bayonet style sockets. The bayonet #47 light sockets sit lower in the bumper body. This prevents the bulbs from burning the back side of the bumper caps.

    Fixing Pop Bumper Playfield Wear.
    If you have excessive playfield wear around the pop bumpers, there is an easy fix. Match the playfield paint and apply it to the bottom side of a new (non-adhesive backed) trim platter. Then when the trim platter is installed, it covers the playfield wear with the same color as the playfield, shown through the clear mylar. A very clean fix without altering the playfield itself. (But unfortunately the paint will eventually wear away from the trim platter.) Another way is to just paint the playfield itself with acrylic water based paint. Then when done cover it with a new adhesive mylar trim platter.

Left: Ready to add a new light bulb.
Right: The finished product.


    Re-assemble from the top of the playfield. If your replacement bumper skirt has a small "tit", it goes towards the top of the playfield (it stops the ball from balancing on the top edge of the skirt). Secure the bumper body to the playfield with its two screws. Then from underneath the playfield, put the locknuts back on the rod & ring assembly. Do NOT over-tighten the rod and ring locknuts, or you will break the rod! Re-solder the light socket.

    Clean the Spoon Switch.
    If you did install new bumper skirts, the bumper switch that the new bumper skirt activates will need re-adjusted. This switch is called the "spoon" switch (because the bumper skirt's "rod" rides inside its spoon-like receptical). Before you do that, remove that entire spoon switch assembly from the game. Note the crud that lives inside the "spoon". This accumulates from (wrongly) lubricating the spoon. Clean the crud out with alcohol and leave this DRY (though some people say to lub the spoon with white grease, I disagree, as it will only attract dirt). Polish the surface with 1000 grit sandpaper (or higher grit). Re-install and adjust the bumper skirt activated spoon switch.

    Note if there is too much tension on the skirt's "rod" from the spoon switch, this will cause the "rod" not to center. There should be just a bit of tension, and no more. Also make sure the rod doesn't ride outside of the spoon switch too much (or the skirt switch will stick on, and lock the pop bumper coil on). You will have to move the position of the spoon switch to adjust this.

    For a final touch, install new pop bumper caps (if available for your game). At a nominal cost, they really make your game look sharp. Save your original pop bumper caps.

3o. Slingshots.
    Slingshots are devices that are generally found just above the main flippers at the bottom of the playfield. They are usually set at an angle in such a way that they kick the ball to the opposite side of the playfield as well as up the playfield. When the ball hits the rubber in front of the slingshot, a switch closes which activates the slingshot coil. As the coil plunger is pulled down into the coil the kicker arm is propelled forward by lever action to shoot the ball away "like a slingshot". There is a second scoring switch under the playfield that closes as the slingshot coil reaches its end-of-stroke. This switch usually connects to a one or ten point relay which does the scoring.

Slingshot diagram from Bally.

    On 1950s Gottlieb woodrails, the slingshot mechs are slightly different. Instead of using a plunger/link mech, the plunger connects directly to the "T" kicker mech via a hardened rollpin. The slot which the rollpin moves wears a groove (the "T" kicker mech is not hardened), which binds the rollpin, causing the kicker "T" arm to bind. The best solution is to replace this entire setup with the more 'modern' (late 1950s) slingshot kicker assembly.

Left: original 1950s Gottlieb slingshot assembly.
Right: 'newer' style replacement slingshot assembly.
(Compare how the plunger attaches to the "T" mech.)

3p. Roto-Targets and Vari-Targets.


    Roto-targets are another type of stepper unit. They don't require a lot of maintenance, but it's a good idea to clean them to ensure good rotation. It's not uncommon for a roto to only spin a number or two when it's dirty. A good clean roto target will spin 180 degrees (or more) if properly maintained. They also must be aligned so the rivets line-up with the target fingers. Otherwise hitting the numbers with the ball on the playfield will not register a score.

Roto-target from Flipper Parade.


    Vari-targets are basically a mini stepper unit with only a reset coil. The playfield ball is what advances the vari-target, and a relay coil resets the vari-stepper back to the reset position. If the vari-target won't fully reset, most Gottlieb EM games will spin the score motor constantly until the reset is complete.

    Clean the vari-target like any other stepper. That is, clean the rivets with 600 grit sandpaper and lightly lubricate with Teflon lube. Make sure the unit resets. Added spring tension may be required, but do not go crazy as it will make hitting the target with the ball more difficult. The spring tension is adjustable. There are three screw positions for the spring anchor, so the vari-target can be 'dialed in' to just the lightest spring tension needed to reset the target.

Vari-target used in many 1970s Gottlieb EMs.

    Note that with the playfield "up", the vari-target will require more spring tension to reset than with the playfield "down" and in the play position. Just keep that in mind, and test the vari-target's reset with the playfield down.

Horizontal roto target as used in 1967 Kings of Diamonds/Diamond Jack,
and the roulette wheel used in 1967 Super Score/High Score.

3q. Drop Targets.
    Gottlieb Drop Targets.
    I will be talking about Gottlieb drop targets in this section because they were the primary user of drops. Though Bally used drops too (and to a lesser extent Williams), Gottlieb made extensive usage of huge banks of drop targets during the 1970s. The first Gottlieb game to use "modern" style drop targets was Crescendo (5/70). But the format really was used in a big way in games like Gottlieb 2001, Dimension (10*2 drops), and Eldorado, Gold Strike, Target Alpha, Solar City (10+5 drops), and Hot Shots, Big Shots (7*2 drops), and Sheriff, Lawman, Atlantis, King Pin, Pin-Up, Jack in the Box, Jumpin Jack, (10 drops). These games all used one or two big banks of drop targets.

A bank of TEN drop targets on the 1971 Gottlieb 2001.

    On these large drop target banks with more than 6 drop targets, Gottlieb used *two* coils to pull in the reset arm to reset all the drop targets. This put even stress on the target reset arm. Otherwise the reset arm would bend or crack due to a cantilever effect on the long reset arm. The pivot point that the reset arm rotates was a 3/16" metal rod with two metal push-nut caps or E-clips (to keep the rod in place). At the point where the reset coils pulls their levers and attach to this rod, the rod can often wear and eventually break. I've seen this happen on both ends of the rod (see picture below.)

On a Gottlieb 2001, here is an unbroken pivot point for the reset arm.

The same Gottlieb 2001 (other target bank), and the pivot point for the reset arm has
sheared the metal rod. This means the drop targets will not reset.

Here's the metal rod removed from the Gottlieb 2001 target bank.
Not much more and it would have sheared off the end of the rod!
This obviously needs to be replaced.

    To replace the broken pivot rod in the drop target bank is mandatory. If it's not done, the targets will never reset correctly or consistently, and could damage other drop target parts.

    To replace the rod, just go to the local hardware store and buy a length of 8-32 threaded rod, and two 8-32 nylon locknuts. Cut the rod to the desired length, and thread one of the locknuts on the end. Then push the new rod into place (don't remove the old rod first). As the new rod is pushed into place, it should push out the old rod simultaneously. This means less work for you, as the new rod will go right through all the target assembly holes without having to disassemble anything. Go slowly and don't miss any holes. When the new rod is fully in place, attach the other 8-32 locknut, and you're done.

Installing the new threaded 8-32 rod into the drop target assembly.
This procedure will push the old rod out.

Here's the new threaded metal rod in place with its 8-32 locknut.

    Preventing the Drop Metal from Breaking Again.
    To avoid metal fatigue in the future, adjust the reset coils for the drop target bank. To do this, loosen the four machine screws securing the reset solenoid(s), then press the reset plunger to its limit by hand. At the same time press the back of the solenoid and move the whole assembly together back until the bank just latches. Now tighten the screws. What you are trying to do is adjust the solenoid so it bottoms out before the bank link, but have enough stroke for a successful reset. (Some tweaking may be needed.) This will prevent a lot of metal fatigue and breakage in the future.

3r. Flippers.
    Rebuilding EM Pinball Flippers.
    Flippers are the interface between you and the game. Having good strong flippers is mandatory. The parts that are in the game are probably 25 years old or older. Here's the parts needed for flipper repair. One of each part is needed for each flipper. Note do NOT go to hotter flipper coils as a first step in making your flippers stronger. Instead rebuild the flippers first (new coil sleeve, plunger/link, nylon playfield bushing, etc.) If you're still unhappy with the flipper power, THEN change to "hi-tap" or/and change to more powerful flipper coils (but if you can get the ball to the top of the playfield, then as a general rule your flippers are powerful enough.) Also note that increasing the flipper travel can also make the flippers a bit stronger.

    • Mandatory: Nylon flipper coil sleeve - if this sleeve cannot be removed from the original flipper coil, then a new flipper coil is also needed. Gottlieb part #A-5064 (1 21/32") or A-5065 (1 7/8"). #5 pictured below.
    • Mandatory: Nylon thru-the-playfield flipper bushing. Gottlieb part #A-2408. #0 pictured below.
    • Mandatory: plunger and bakelite link. These are usually sold together. I don't suggest trying to assemble the plunger/link yourself unless the link is not available (common on a lot of games, where you will have to make a new link yourself from bakelite). The original plunger is often mushroomed at the end, and can often be filed smooth again. Gottlieb part #A-3396 (game dependent). #6 pictured below.
    • Often needed: EOS (End of Stroke) switch. Original contacts can often be filed. #1 pictured below.
    • Often needed: Cabinet switch. Like the EOS switch, this one takes a lot of abuse too. Original contacts can often be filed. Not pictured below.
    • Sometimes needed: flipper pawl return spring (there are often separate right and left side versions). Gottlieb part #A-3328 (left), A-3329 (right). #8 pictured below.
    • Sometimes needed: flipper pawl (specify right or left side for some games). For Gottlieb, it is best to use the "old style" pawl (more explained on that below). Make sure there is no play in the pawl collar and pawl pin - This is very common with pre-1956 Gottlieb pawls where the pressed together parts become lose (see the blue arrows below). Sometimes hammering the pawl collar's pressed area will tighten that up. If the pawl pin is loose, Pinball Resource sells new pins (but they will have to be pressed into the pawl). Gottlieb part #A-5982/A-5983 or A-3399/A-3400. #3 pictured below (old style).
    • Sometimes needed: flipper shaft. Gottlieb part #A-6888. On the original Gottlieb flipper shaft, the part that mounts under the 2" flipper is separate from the shaft. Often the slot where these two parts meet wears and you get slop. Replace with a new shaft if this is the case. #7 pictured below.
    • Sometimes needed: plastic flipper bat (the part the ball hits). Gottlieb part #A-5095 or A-5394 or A-5393. #2 pictured below.
    • Sometimes needed: flipper coil. Gottlieb part #A-5141. #4 pictured below.
    • Rarely needed: upper flipper coil mounting bracket. Gottlieb part #A-5147. #9 pictured below.
    • Optional: Coil stop. Gottlieb part #A-5189. #10 pictured below. Also available, just the core of the coil stop and aluminum nut, without the mounting bracket. A money saving idea is to swap the Replay unit coils stops with the flipper coil stops. Gottlieb part #A-4862. #11 pictured below.

Gottlieb flipper rebuild parts. The blue arrows on the pawl shows
points that can become loose. This will need to be addressed for good
flipper action.

  1. Nylon flipper bushing.
  2. EOS switch
  3. Flipper bat
  4. Flipper pawl (arrows show points where pawl can become loose)
  5. Flipper coil
  6. Nylon coil sleeve
  7. Flipper link (bakelite) & plunger (metal)
  8. Flipper shaft and shoe
  9. Return spring
  10. Coil support bracket
  11. Coil stop
  12. Coil stop (removed from accompanying bracket)

Flipper diagram from Bally.

    If you are keeping the same flipper coil, replace the flipper coil's nylon sleeve (a thirty cent part). Also always replace the metal plunger and link with a new one. Often the plunger link is metal - the replacement should be bakelite (a brown fiber-ish plastic), which will wear better and is lighter weight (for better flipper performance, as it takes less energy to put a lighter weight bakelite part in motion than a heavier metal part). These new parts will give optimal performance as there won't be any "slop" to absorb flipper energy.

Gottlieb Spot Bowler showing an energized flipper with a ball cradled in the "V".
I like a good "V" on two inch flippers so I can cradle the ball. This may require
some increase in flipper travel.

    When rebuilding the flippers, it's not a bad idea to replace the coil stops. New coil stops will make your flippers quiet when holding the cabinet flipper button in. Also sometimes the old coil stops are magnetized enough to hold the flipper in the up position. You can buy new stops, or just rotate the flipper and backbox Replay unit coil stops. The replay unit gets very little use, so its coil stops (two coils on the replay unit) should be in excellent condition. Just move the Replay stops to the flippers, and the flipper stops to the Replay unit.

    I also like to increase the flipper travel slightly when I rebuild EM flippers. I want to be able to hold the flipper in the energized "V" position, and have good flipper bat angle to cradle the ball. To increase travel I usually bend the resting flipper stop slightly. This will require a reposition of the flipper bat's resting position, but will give more travel.

On this Gottlieb Spot Bowler the original metal flipper link was replaced
with a bakelite link which I made. Note the EOS switch activation arm on
the replacement.

    Many EM games have wear marks on the playfield from the flippers. This is known as "flipper drag". This is caused from worn or cracked nylon flipper bushings, which go through the playfield. These nylon flipper bushings should ALWAYS be replaced to stop flipper drag. New flipper bushings are slightly taller than originals to prevent this problem.

Original flipper link sitting on top of some raw bakelite. The new link will be
lighter weight and actually wear better. Bakelite is the ideal material for this chore.
Note the blue arrow shows where the hole in the link has become oblong. This puts
play in the system, making the flippers sloppy and weak. The new EOS switch activator
will be a 8-32 x 3/4" bolt covered in heat shrink tubing.

    Also make sure the flipper return spring is not too tight. There should be enough spring to return the flipper, and no more. Too much return spring and it is only being fought by the flipper coil. You can often adjust the flipper spring strength in 1/3 turn increments (by moving the spring's anchoring position to another of the three screws on the flipper bushing). Lastly, make sure the EOS (end of stroke) switch is adjusted correctly. It should open about 1/8" when the flipper is fully "flipped". Also file the EOS switch and cabinet flipper switch clean with a metal file.

Gottlieb Spot Bowler with two new flipper links which I made. New nylon playfield
bushings are also installed. Also new yellow dot flipper coils. There's no play in
this flipper system, as everything is tight and fresh.

    You may also want to install new Gottlieb EM "hi power yellow dot" flipper coils (as shown in the above picture). Provide about 5%-10% more power (probably not necessary if you have done all the above maintenance.) The normal power side to a A-5141 coil is 1.9 ohms resistance. The yellow dot high power flipper coils are just 1.0 ohms resistance in comparison (which is a moderate increase in power).

Rebuilding the flipper with new plunger and link
on a 1960s Gottlieb. Remove the coil stop or "C"
pin to release the parts.

    EM Flipper Rebuild Instructions.
    Work on one flipper at a time. This way if there is some issue, you can always look at the other flipper for comparision. These instructions have 1950s and 1960s Gottlieb flippers in mind, but apply to most other game makers and eras of EM flippers.

    1. Put the playfield in the "up" position, leaning it against the backbox. Find a small step stool to stand on.
    2. Put a white towel over the bottom panel of the game. This way if a small part falls, you can find it easily on the towel.
    3. Remove the coil stop (lower bracket) from the flipper coil. This will allow the removal of the flipper coil (just slide the flipper coil off the plunger).
    4. Slide the old coil sleeve out of the flipper coil. If the coil sleeve will not come out easily (I use a yellow handled nut driver to push the old sleeve out of the coil), replace the entire coil (which should come with a new coil sleeve).
    5. If using the original coil, inspect the three wire lugs. Visually check the three lugs and make sure the tiny coil winding wires are attached to the lugs. The center lug (the common lug) should have both a thin and thick winding wire attached to it. The other two outside lugs should have a single winding of wire attached to it (one thin, one thick). If any of these wires are broken, replace the coil. (Though sometimes one winding can be unwound, the wire sanded to remove the insulation, and resoldered to the solder lug.) A multi-meter (DMM) can also be used to check the coil. With one lead of the DMM on the center common lug, and the other on the thick wire outside lug, about 4 ohms should be seen. Move the outside DMM lead to the thin wire lug, and about 100 ohms should be seen. The game wires going to the center flipper coil lug may need to be removed to get accurate DMM readings.
    6. On pre-1969 Gottlieb games, remove the spring clip from the flipper pawl, which holds the plunger/link to the pawl. The plunger/link can now be removed. A brand new plunger/link should be used. On 1969 and later Gottlieb games, the flipper pawl is attached to the plunger's link by a roll pin. This complicates things a bit. See below for more information*.
    7. Remove the flipper pawl from the flipper shaft. Usually there are two allen screws or small 1/4" screws holding the pawl to the flipper shaft. As the pawl is removed, the flipper spring will also need to be unwound/removed.
    8. Remove the flipper/flipper shaft from the top side of the playfield. It should freely pull out.
    9. Undo the three screws from under the playfield that hold the nylon flipper bushing. Note which screw retains the flipper return spring. Throw the original bushing away, and replace with a new nylon flipper bushing. The new bushing should stick through the top of the playfield about 1/8". Re-secure the bushing with the same three screws, and reattach the flipper return spring on the same screw.
    10. Replace the flipper shaft through the nylon flipper bushing on the top side of the playfield.
    11. Replace the flipper pawl onto the flipper shaft. LIGHTLY tighten the two pawl screws.
    12. Optional. I like to bend the resting flipper pawl/link metal guide slightly to give the flipper bat slightly more travel. This gives a bigger "V" for the flipper when it's held (energized), making it easier to craddle the ball. A good thing on 2" flipper games.
    13. Reattach the flipper return spring on the flipper pawl. The spring should have enough power to move the flipper back to the home position, but not too much power. If too much spring power is used, the flipper coil will just have to fight the spring, weakening the flipper. Adjust accordingly.
    14. Attach the new plunger/link on the flipper pawl using the spring clip or an "E" clip. (If this is lost, they are readily available at any hardware store.)
    15. Hold the flipper coil in place against the upper bracket, and replace the coil stop.

    The flipper is basically rebuilt, but will need some minor adjustment. Repeat the above procedure on the other flipper first.

    After both flippers are rebuilt, lower the playfield. Now align both flipper bats as you would like them (I like to bend the resting metal flipper pawl/link stop slightly to increase travel on 2" flipper games). Since the pawl screws are only lightly tightened, the flipper shafts should move in the pawls to allow easy alignment. Compare the engized flipper position for both flippers to make sure there is good flipper travel, and that the two flippers are symmetrical. After the flipper bats are aligned, lift the playfield and tighten the two screws on each flipper pawl. Lower the playfield and double check the flipper bat alignment.

    Note there is an adjustable plunger/link stop on many games (especially Gottlieb). It's purpose is to change the amount of plunger travel, allowing the left and right flippers to be adjusted so they have the same amount of travel and align in both the resting and extended positions. (Again I find it easier to just bend the resting flipper stop if additional bat travel is needed (or to make the right and left flippers symmetrical, instead of adjusting the screws.)

    The last step is to check and adjust the EOS switch. First inspect the EOS switch. If the EOS contacts are pitted or burned, replace the entire switch. If they are usable, file the EOS switch contacts with a metal file to remove any pits or burns.

    Now move the flipper to the fully energized position, by moving the flipper plunger where it meets its link. The EOS switch should open about 1/8" when the flipper bat is extended. Adjust the switch as needed. Note there should be a piece of "fish paper" on the EOS switch blade that touches the flipper pawl. This electrically isolates the pawl from the EOS switch.

    Also check the flipper button cabinet switch for pits and burns. File as needed, replace if it's in bad condition.

    * On 1969 and later Gottlieb pin games, the flipper pawl style was changed. Prior to 1969, a large round 1/4" pin was on the pawl, and the plunger's link just slipped over this pin, and was secured with a spring clip. This was very convenient to work on, requiring no tools to remove and install the plunger/link to the pawl. But in 1969, Gottlieb changed the flipper pawl so now the plunger's link slide between two pieces of metal, and the pawl was secured to the link with a roll pin. This made removing the plunger/link assembly much more difficult, as now the roll pin had to be hammered in and out of place.

    In addition, when installing a new plunger/link into the 1969 and later pawl, if too much "hammer" was used on the pawl's roll pin, it could bend the two pieces of surrounding metal, binding the link, and making the flipper stick. Really the right way to deal with the roll pin is to use an inexpensive $10 press punch tool, but most people don't have that tool, and hence use a nail and a hammer. Another complication is the 1969 and later style pawl is NLA (no longer available), where the pre-1969 style has been reissued and is available.

    The solution to this problem is simple. Replace the 1969 and later Gottlieb style roll pin flipper pawls with the older spring clip style pawl. The older pawls retro-fit on 1969 and later games with no modifications (the geometry and sizing is identical). The only difference is the plunger's bakelite link hole that attaches to the pawl must be made larger (or when ordering new plunger/links, specify the old style pawl and they will come correctly drilled). This solution solves the availability problem (old style pawls are readily available), and installation/removal of the plunger/link is much easier.

The EOS switch and how it interacts with the flipper coils,
and the general flipper wiring. This is the same for Bally,
Gottlieb and Williams. Picture by Al Garber, rest his soul.

    EM Flipper Coil Strengths.
    Standard vs. Yellow Dot vs. Orange Dot.
    The standard Gottlieb EM flipper coil from basically Humpty Dumpty (1947) to 1979 was the A-5141. (Though Gottlieb did use flipper coil A-1546 too - it's the same coil just does not have a replaceable nylon coil sleeve). The A-5141 coil is 1.9 ohms for the power side of the coil, using 450 turns of #22 wire. Though this is a decent strength coil (assuming all the flipper parts are rebuilt and new), sometimes you just want "a little more" out of the flippers (especially on 2" flipper games).

    Because of this, Steve Young of Pinball Resource and Donal Murphy of Electrical Windings came up with a stronger Gottlieb EM flipper coil. It is known as the A5141 "yellow-dot" coil. The only difference between a standard A5141 and a "yellow-dot" is the power winding. The yellow-dot A5141 has 300 turns of #20 wire, giving a power side coil resistance of 1.0 ohms (lower resistance mean less current restriction and a stronger coil). Note this is the identical specs as used on late 1970s Williams EM games and their FL-300-20/28-400 flipper coil. So why not use a Williams FL-300-20/28-400 on Gottlieb games? Well the Williams coil frame size is 1/16" longer. So to put a Williams flipper coil in a Gottlieb requires some "tweaking" and adjusting. Instead Steve/Donal just used the Williams flipper wire specs on a Gottlieb coil frame to solve this problem.

    But what if you're in a position where the original Gottlieb a5141 is too weak for your tastes, but the a5141 "yellow-dot" is too strong? This has happened to me on a couple Gottlieb EM drop target games, where I wanted more "punch" from the flippers, but the yellow-dot coil was just too strong and broke drop targets. The solution is to use a Williams flipper coil, the FL-21-375/28-400 (this coil pre-dated the stronger Williams FL-20-300/28-400.) The Williams FL-21-375/28-400 is stronger than a stock Gottlieb A5141, with 375 turns of #21 wire power winding of 1.3 ohms (stronger than A5141's 1.9 ohms, but not as strong as yellow-dot's 1.0 ohms). This is a nice "compromise" coil, though the fit into a Gottlieb flipper mech is a bit tight because the WMS coil is 1/16" longer. (Steve Young has told me he will eventually wind these coil specs on a Gottlieb coil frame, solving this problem, and these will be called "orange dot" A-5141 coils.)

    So in summary, on Gottlieb EM games and post-1962 Williams EM games running at 30 volts:

    • Gtb Stock: a5141 (450 turns #22 wire, 1.9 ohms)
    • Gtb/Wms Stronger: FL-21-375/28-400 (375 turns of #21 wire, 1.3 ohms), aka "orange dot".
    • Gtb Strongest: a5141 "yellow-dot" (300 turns #20 wire, 1.0 ohms)
    • Wms Strongest: FL-20-300/28-400 (300 turns #20 wire, 1.0 ohms). This is the same coil strength as a Gottlieb A5141 "yellow dot", but wound on a Williams coil frame.

    Now what about Bally and 1948-1962 Williams EM games? These games run their coils at 50 volt (instead of Gottlieb's 30 volts), so the coil specs are different. The strongest Bally EM flipper coil, as used on late 1970s Bally EMs like Captain Fantastic, is the AF-25-500/28-1000. This coil uses 500 turns #25 wire for a resistance of 3.3 ohms. Note the resistance is higher than Gottlieb flipper coils, and that's because Bally games run on 50 volts (instead of 30 volts). I use the AF-25-500/28-1000 coil on all my Bally EM games and my 1962 and prior 50 volt Williams games. It's about as strong as you'll ever need for these games.

3s. Bally Zipper Flippers.
    Zipper Flippers are a type of 2" flipper invented by designer Ted Zale and used on a number of Bally EM pinball games from 1966 to 1973. The flippers would physically move together, closing the gap between them so the ball would not drain. The Bally games that used this really neat mechanical flipper design included Bazaar (10/66), Capersville, Rocket III, the Wigler, Surfers, Dogies, Dixieland, Joker, Cosmint, RockMakers, Mini-Zag, Alligator, Cosmos, Op-Pop-Pop, Gator, Joust, 4 Queens, Four Million BC, Fireball and Nip-It (7/73). Williams also copied the designed for four of their games: Daffie (5/68), Student Prince, Doozie (add-a-ball of Daffie), and Hayburners II (8/68, and the only zipper flipper game to use 3" flippers, but Williams was forced to stop using zipper flippers because Bally was threatening legal action).

    Zipper flippers are a fairly complicated mechanical device, and do require service. I will show some of the high-wear parts (other than the obvious stuff that would normally wear on any flippers). Below is the zipper flipper removed from a Fireball.

    The "close" coil on the zipper flippers is very unique and much different than other standard pinball coils. Originally in the first couple Bally games with zipper flippers, this coil ran at 120 volts with part number E-184-234 (at 20 ohms), but it was changed to 50 volts with part number E-184-239 (9 ohms). The original 50 volt version was made by Comar Electric Company, and had the marking "C 11027" on the coil, often followed by "E-184-239". Also marked on the coil was "50-60c Int Duty". The ohm reading on this 50v coil should be about 9 to 10 ohms. If it's less than 5 ohms, the 1.5 amp fuse located next to the zipper flipper mechanism will certain blow when the pull in coil is engaged. Note that Guardian Electric made a replacement coil for the original Comar coil. The part number on the Guardian 50 volt coil is usually E-184-277 and/or A420-064506--00 (and often with a 1974 date code), and the resistance of this replacement is about 5 ohms (which is pushing the lower end of the resistance scale for a 50 volt coil.) Note Guardian also sold a 24 volt version too. This lower volt version can be used on 50 volt Bally games, but a 5 or 10 watt resistor would need to be used in series to increase the coil ohms (otherwise the coil will destroy itself.)

    Speaking of fuses, always make sure the zipper flipper pull in coil is directly fused. There should be a fuse holder right next to the zipper mechanism. The usual fuse is 1.5 amp slow blow though 2 amp slow blow is also acceptable.

    In the 1980s when Bally released the solidstate game Medusa (which used zipper flippers), the pull in coil was significantly changed. So unfortunately that coil won't work in the original Bally EM zipper flipper games.

Zipper Flippers removed and "open". The flipper bats are added here, but are actually
"upside down" (but it shows how the flipper bat are incorporated into the design).

Zipper Flippers removed and "closed". Notice the gap between the bats is closed.
The two metal arms that make up the "V" do like to wear, along with their pivot points.
On this unit they really need to be replaced (you can see the attachment bolts have
been incorrectly replaced, but the unit is working decently, so it's not a total hack).

Zipper Flippers removed and "open", from the top side. This is actually how the flipper
bats are really installed when the unit is in the game. Note the two large washers with
screws. These adjust the tension on the moving flipper base plates. There are two fiber
washers used under the metal washer (one directly under the washer, and the other
between the moving flipper base plate and the stationary plate). These adjustment
screws must be tight enough for the baseplates to rotate, but not too tight to bind.
There is a jam nut on the other side of the stationary plate to hold the adjustment
screws in their place.

Zipper Flippers removed with blue arrows showing the moving base plate slots. These
slots have a bushing inside of them. The bushing and the slots themselves like to wear.
I have found that a good replacement bushing is from Williams WPC flippers (used
inside the flipper link as a flipper link Spacing Bushing, part# 02-4676, not shown here),
and is slightly larger than the original Bally part. This takes up a lot of slack in the worn
moving slots for the baseplates. I also used a Dremel and slightly smoothed out the
slots, as they has some low points. This and the new bushings really help. The nylon
playfield bushings have to be trimmed a bit so the slot bushing washer does not
interfere with the base plate movement (probably because these washers were not
original, as shown by the red arrows).

Zipper Flippers removed shown from the side. At the right of the picture is the
high-powered 50 volt solenoid that pulls in the zipper flippers. This latches
on the nylon "tooth", holding the flippers closed. To release the flippers back to open,
the relay pulls in, unlatching the clog. Sometimes the pull-in solenoid
does burn. The blue arrow shows this coil, which on this game was under 1 ohms (a dead
short). This coil had to be rewound or replaced. Notice the red arrow in the picture
too. The lugs on the release relay can short against the metal frame. This was wrapped
in electrical tape to prevent this.

    Rewinding the Comar Zipper Flipper Pull In Coil.
    Since the original pull in coil for the zipper flippers is unique and largely unavailable, if it is less than 5 ohms in resistance, there isn't much choice but to rewind it. This is not necessarily an easy job, but it's far from impossible.

Here's the Zipper Flipper 'close' coil originally used in Bally EM games. The blue arrows show the three rivets that hold the coil together.

    The first task is to drill out the three rivets holding the coil together. Use a 7/64" drill bit for this. (Drill straight through the coil too, as we need to enlarge these holes a bit for when we re-assemble the coil.) After the rivets are removed, the entire coil assembly can be disassembled. After the rivets are drilled and removed, the U shaped copper retainer clip should be removed. Then the two long U shaped clips are slid out of the center of the coil. This will release the coil body from the metal plate frame.

The Zipper Flipper 'close' coil with the rivets drilled and disassembled. Note the U shaped copper retainer clip in the upper right, and the two long U channel retainers below it. The "T" clips are at the upper left of the picture.

    What you end up with is a square coil bobbin. It is kind of like an onion, and will need to be de-layered to get at the wire. After the wire is exposed, it can be unwound and discarded. What happened here is the heat from the coil baked the enamel paint insulation off the wire, causing it to internally short. We will have to replace this wire and re-wind it back onto this square coil frame.

The Zipper Flipper coil frame after removing the outside onion layers. Be sure to save the fish paper with the two coil lugs attached. You'll need this later.

    Below is a picture of the coil frame with all the wire removed. The next step is to use the correct wire, and re-wind it back onto this coil frame. I found a standard pinball coil that used #28 guage wire. This seemed to be the perfect wire gauge for this task. Intially I used #26 wire (more common), but that is too thick and it's too difficult to get it wound correctly onto the coil frame. So find a pinball coil with the prefix "28-" and that is your donor wire coil, which will ultimately re-populate our square zipper flipper coil frame.

The Zipper Flipper coil frame after removing the burnt wire.

    To re-wind the coil, you'll need someone to help you. Secure the square coil frame to a variable speed drill. I used a 1/2" wood bit and some pinball rubbers to do this. Your helper will need to have the donor #28 wire pinball coil on a pencil. Make sure there is good tension and slowly wind the wire off the donor pinball coil and onto the square coil frame at a slow speed. As the drill slowly turns, the helper can guide the wire onto the square coil frame, moving back and forth to evenly fill the bobbin.

Using a drill and a helper to wind the #28 coil wire off an old pinball coil and onto the square Zipper Flipper coil frame.

    Note you should not over-wind the square coil bobbin. This bobbin must fit back into the metal frame of the pull in coil, so the wire can not exceed the outside size of the bobbin. I wound the coil about 3/4 full and then did a quick resistance check on the wire. The idea is to get about 10 ohms of wire onto the bobbin without over-winding the bobbin. To check resistance you'll need a good digital multi-meter (DMM) set to low ohms. Also you'll need to scrape the enamel paint off the wire at small points so you can get a ohm reading. Remember you want about 10 ohms worth of #28 wire! After you have 10 ohms worth of wire, you can re-use the original coil lug fish paper and solder the wires to the lugs. Then wrap a thin layer of electrical tape around the bobbin to hold it all together.

The square zipper flipper bobbin re-wound with fresh #28 wire. After the wire ends are soldered to the original coil lugs, a thin layer of electrical tape is wrapped around the bobbin to keep it all nice and tight.

    With the square coil bobbin re-wound, now it's time to re-assemble the coil. Slide the square bobbin into the metal frame, and insert to two long U shaped pieces inside the coil bobbin. After these are in place, the copper U retainer clip can be inserted. THen the two "T" retainers can be put in place. Three #4 machine screws 3/4" long and nuts will replace the original metal rivets.

The square zipper flipper bobbin re-wound and re-assembled using #4 machine screws.

    From what I've found, re-winding the original zipper flipper pull in coil with new #28 gauge wire works very well. And I like the 10 ohm resistance value better than the 1974 Guardian made replacement coils (which are only 5 ohms.)

    Rewinding the Guardian Zipper Flipper Pull-in Coil.
    If your Bally game has a Guardian zipper flipper pull in coil that is shorted, these too can be rewound. It's more involved than re-winding the original Comar coil. This is because the coil itself on the Guardian is incased in plastic. But it is still possible, and below are the steps needed to do this.

On the Guardian coil, just like the Comar coil, the three rivets will need to be drilled out with a 7/64" drill bit. After this is done, the long U retainer clips can be pulled out and the coil bobbin released from the metal frame.

Now comes the tricky part. Since the coil is incased in plastic, a band saw is needed to cut the plastic on four sides to reveal the coil windings. I know it seems pretty invasive (which it is!), but it's the only way to get the old wire off the bobbin.

At this point you'll need to scrap and cut all the old wire off the bobbin. When done it will show the center core of the bobbin, which we will re-use and re-wind.

Just like on the Comar coil, using a drill and a donar coil with #28 wire, the original Guardian coil bobbin can be re-populated with new wire. The trick is to get the coil to 10 ohms. You'll need to stop along the way and check the resistance with a DMM set to low ohms. After the coil bobbin is re-populated with new wire, electrical tape can be wrapped around the bobbin to secure the new wire.

Finally the bobbin can be re-inserted into the metal frame, the long "U" brackets installed, and the whole thing secured with new #4 machine screws and nuts. Note the small metal brackets shown at the bottom of the picture below will no longer be used (as the plastic bobbin frame will not support them.) I re-used the cut off coil lugs and tape it to the side of the re-wound coil, so there's something to solder the coil wires. Now the re-wound Guardian coil is ready for use in your zipper flipper game.

4a. Finishing Up: Playfield Glass

    Most EM games from 1947 to present use a standard playfield glass size. This is 21" x 43" x 3/16" tempered glass (do NOT use plate glass as it is a hazard and very dangerous). An exception to this size rule are Bally pinballs 1963 to 1974, and those with "framed" playfield glass, which have a metal frame around the glass (used 1967 to 1973 on games like Fireball). This Bally glass is 21" x 41.5" x 3/16" tempered glass (even on pre-metal frammed glass), until they stopped using the metal frammed glass (about 1973). Remember *always* use tempered glass that is 3/16" thick.

4b. Finishing Up: Setting your EM to Free Play
    In case you're wondering, there is no factory setting or adjustment to set your EM to free play. You'll have to cheat to make your game so it doesn't require quarters to play. In order to do this, you'll need to find the credit stepper wheel in the lightbox. Pretty easy to identify: it has a wheel with the credit numbers on it!

Bally credit wheel: adjust one switch permanently closed when credit unit is at
"zero" credits for free play (right red arrow). The blue arrow (left) is the max
credit switch, which should be normally closed (otherwise the game will not add
any more credits).

    Bally Free Play.
    There is only one switch that controls free play on a Bally game. Set the credit wheel to zero credits (shows zero credits through the backglass). On the stepper unit there will be a knotched wheel with a fixed pin sticking out. This pin should have opened a switch only when the credit wheel is at zero credits. Adjust this switch so it is permanently closed (or use a jumper wire), regardless of the credit wheel position. Note there may be a second movable pin (with a slotted head). This is the maximum credits pin. Do not change the switch this pin contacts. Your Bally game is now set on free play.

Williams credit wheel: adjust the top switch (red arrow) permanently closed when
the credit unit is in the "zero" position for free play. The lower switch (blue arrow)
is the max credit switch, which opens at maximum credits not allowing the credit
unit to add any more games.

    Williams Free Play.
    There is one switch that controls free play on a Williams game. Set the credit wheel to zero credits (shows zero credits through the backglass). On the stepper unit there will be a knotched wheel with a pin sticking out. This pin should have opened two switches only when the credit wheel is at zero credits. Adjust the top switch (or use a jumper wire) so it is permanently closed, regardless of the credit wheel position. Note there may be a second movable pin (with a slotted head). This is the maximum credits pin. Do not change the switch this pin contacts. Your Williams game is now set on free play.

Gottlieb credit unit: adjust the smaller contact "zero" position switch (red arrow)
closest to the backglass permanently closed for free play. The larger contact switch
next to it has little consequence, but should open at the credit unit "zero" position.
The switch at the right (blue arrow) is the max credit switch, which should open when
the credit unit reaches maximum credits.

    Gottlieb Free Play.
    There is one switch that controls free play on a Gottlieb game. Set the credit wheel to zero credits (shows zero credits through the backglass). On the stepper unit there will be a notched wheel with a pin sticking out. This pin should have opened two switches only when the credit wheel is at zero credits. Adjust only the smaller of the two switch contacts (located closest to the backglass) so it's permanently closed (or use a jumper wire), regardless of the credit wheel position. The other switch should operate normally, and be open when the credit wheel is at zero credits. Note there may be another movable pin (with a slotted head). This is the maximum credits pin. Do not change the switch this pin contacts. Your Gottlieb game is now set on free play.

Gottlieb used a "half moon" credit unit on some games, as shown here.
Only one switch needs to be permanently closed when the credit unit is at
"zero" credits to enable free play (the switch with the blue arrow, closest
to the increment coil).

    Add-A-Ball and Novelty Game Free Play.
    In 1960, Gottlieb invented something called "add-a-ball". These games awarded additional balls during a game instead of a free game (known as a replay) when the player achieved a certain score. This was done for legal reasons in states that wouldn't allow a player to actually "win" a free game. Wisconsin and New York were the two big add-a-ball (AAB) states, though other areas had these laws too. Also some games are labeled "Novelty" games, and again cannot win any credits, hence they don't have a credit unit.

    AAB and Novelty games are pretty easy to identify; they do NOT have a credit wheel! Also on AAB games, the ball in play designation on the backglass is usually labeled "balls to play" instead of "ball in play". Since you couldn't win a free game, there was no need for a credit wheel. A game starts when the patron put a coin into the coin slot (there is usually no start or replay button on Novelty or Add-a-Ball games). Since there is no credit wheel, the procedure to make an AAB game "free play" is a bit different than a replay game.

Gottlieb AAB Flipper Cowboy. Here the coin switch metal activator rod is
manipulated so the coin return lever (top arrow) presses the coin switches
together (lower arrow), starting a new game.

    Setting free play on an AAB is often as easy as manipulating the coin return button to be the game's "start" button. Some imagination is often required so no new holes are cut in the coin door or the cabinet. Often you can bend the coin switch's activator wire lever so it is moved by the coin return button. This is an easy 30 second modification, which can be easily reversed. Starting the game only requires pushing the coin return button on the coin door.

    Another exception to this is on late 1970's Gottlieb EM games. These games' coin door coin switches do NOT start a new game. A coin is inserted into the coin door, and the start switch must then be pressed to start a new game. Free play on these games is a bit different. You must "double up" the start switch. That is, make the start switch TWO switches. As the start button is pressed, first it closes two contacts that connect to the coin switch (this simulates dropping a coin in the coin door). Then as the start button is pushed further in, it closes two contacts that actually start the game. These two switches must be insulated from each other with fish paper in the switch stack!

4c. Finishing Up: Cleaning and Waxing the Playfield
    Keeping your EM playfield cleaned and waxed is of major importance in game performance. Dirt on the playfield slows the ball down, and increases playfield wear.

    There are a number of products you can use for cleaning the playfield. Millwax comes to mind. Personally, I would avoid this product. Millwax isn't even really a wax. It's a cleaner with extremly small amounts of wax and lots of solvents to keep the cleaner/wax in an easy-to-apply liquid form. It's false protection; you're not waxing your playfield, you're only cleaning it with Millwax. Also Millwax contains petroleum dissolutes, which are probably harmful (and smell bad!). And stay away from all Wildcat products as they crack mylar and yellow plastic parts.

    Personally I like Novus#2 for cleaning EM playfields. It works great, and leaves a great shine. It contains no harmful solvents. It's very gentle, yet cleans fast and well. I buy it at my local grocery store, but you can also get it through most pinball retailers.

    After cleaning your playfield, apply a good HARD wax. Trewax or Meguires Carnauba Wax work great. Both of these waxes are just that; wax! They have little or no detergents or cleaners in them. Notice how difficult they are to remove and polish after they haze (as applied per the instructions)? This is good! It means your pinball will have a hard time getting them off too. I recommend you re-wax your playfield every 100 games with these waxes.

    Also a scratched ball can slow and damage the playfield. Replace the ball if it's not shiny like a mirror. They are only about $1.25 each. Throw the old balls away.

4d. Finishing Up: Playfield Rubber
    Clean WHITE playfield rubber will keep your game in tip-top shape. Many suppliers sell rubber ring kits; just specify the name of your game, and they'll send you the exact rings for it. And don't forget to get flipper rubber, a new shooter tip, and a rebound rubber.

    Do not use black rubber on EM games. It looks bad, is much harder, and hence has different (less!) bounce. Black rubber is designed for the newer, faster Solid State games. Black rubber also creates black dust, so you have to clean the playfield and parts more often.

    Clean rubber has amazing bounce properties. Dirty rubber has seriously reduced bounce. The more bounce, the more fun your game will be. If you want to try and clean your old (only slightly dirty) rubber, you can use WAX or Novus2. Trewax or Meguires Carnauba Wax works great on lightly soiled rubber. Just remove the rubber and wax it. Wipe off the excess with a clean rag. The wax will keep your rubber supple and UV protected. You don't even have to remove the rubber if it's not too dirty. For dirtier rubber, try alcohol. Use a clean rag and wipe the rubber down. As a last resort, for really dirty rubber, lacquer thinner works well. But don't get that near your playfield! It will ruin the paint.

    Gottlieb Rubber Sizes.
    Gottlieb lists rubber part numbers in their manuals, but does not indicate the actual sizes and types of rubber. So below is a list of the rubber parts and sizes.

    Part#Rubber Type
    #E-15Rubber Tip
    #986Rubber grommet - drop target
    #1872Rubber plunger tip
    #2752Rubber grommet - chime
    A-1344Rubber rebound
    A-5240Rubber grommet
    A-10217Rubber ring 3/8"
    A-10218Rubber ring 3/4"
    A-10219Rubber ring 1"
    A-10220Rubber ring 1-1/2"
    A-10221Rubber ring 2"
    A-10222Rubber ring 2-1/2"
    A-10223Rubber ring 3"
    A-10224Rubber ring 3-1/2"
    A-10225Rubber ring 4"
    A-10226Rubber ring 5"
    A-13149Flat beaded rubber ring - 2" small flipper, red
    A-13151Rubber ring - 3" flipper, red
    A-14793Rubber ring - mini post, 23/64"
    A-15705Rubber ring - mini post, 27/64"
    A-17493Rubber ring 7/16"

4e. Finishing Up: Chime Box Repair (Williams)
    The tone of an EM game's chime box is something very sacred. (Well at least to me!) Bally and Gottlieb did a nice job with their chime box - good tone that rings for nearly ever. Williams on the other hand, well, not so much. Williams chime boxes wear out, and the tone turns metallic. It's a gross and sick sound, one that must be addressed!

Another high-wear part on 1970s Williams EM games (Space Mission). This is
the chime "box", which uses three aluminum bars of different lengths for
different chime tones. There is a coil for each bar with a nylon tipped
metal plunger that hits the bar. With time, the hole in the aluminum bar
retaining post that the retaining pin goes through will enlongate and
eventually break (as seen in the bent over post below). If the nylon tip
breaks off the metal coil plunger (common), this problem will happen even
faster. Also note the groove worn in the used retaining pin. A new chime box
and retaining pins will need to be installed, or the old posts and pins
replaced with new metal posts and pop riveted in place (as seen here).
Also note the rubber spacer for the chime has been replaced. If this is
not done, the chime will sound frail and harsh. An old playfield post
sleeve (as used on 1990s pinball games) was cut to replace the old rubber
spacers (two used on each post, one under and on top of the chime bar).

    The first step is to remove each chime bar, one at a time. This is done by bending the hook on the end of the retaining wire, so it can be slid out of the chime bracket. Note it's common for the end closests to the chime plunger to break the chime bracket, so there's nothing for the retaining wire to slide through. Once this happens, nothing short of a new chime box or some welding/drilling will fix the problem. The chime plunger should be inspected. Make sure the metal plunger has a nylon tip! If it does not, it will kick the chime bar to death, and certainly break the bracket that holds the retaining wire in place.

Williams chime box removed from the game, one chime bar removed.
Check that chime plunger for a nylon tip! If missing, replace the plunger.
The blue arrows point to where the original rubber chime gaskets were installed.
For sure these are long gone, making the chime box sound metallic. Replace
these gaskets with rubber plumbing washers (available at Home Depot.)
The red arrows show the original nylon top washers - these are usually
present and re-usable.

Williams chime with two black plumbing washers installed on the metals stays.
These are available at any hardware store.

    The original rubber washers that go underneath the chime bars will definitely be worn out (and probably missing.) This is what makes Williams chime boxes sound so bad, as the metal chime bar bangs on the metal chime box basket, causing a tone equivalent to fingernails on a chalk board. The rubber washers must be replaced. I use rubber plumbing washers, available from Home Depot. An assortment kit of about 100 washers can be bought for about $5. Put one over each of the metal retaining wire posts. Replace the clear plastic tubing over the post. (I usually cut about 1/8" off this clear tubing first.) Then install the original chime bar.

Another angle of the Williams chime box with plumbing washers installed.

Williams chime box with the plumbing washers installed under the chime bar,
and the clear tubing (cut slightly shorter) and installed over the metal stays.

Williams chime box removed from the game, chime bar being reinstalled.

    On top of the original chime bar goes a nylon washer. These are usually intact and re-usable. If they are missing, use a new rubber plumbing washer. Now put the retaining wire bar on top of the chime bar. Push the bar down, then slide the retaining wire through the holes in the chime bar brackets. If the retaining wire is missing or broken, an old clothes hanger can be used to make a new wire.

Williams chime box ready for re-installation.

Williams chime box ready to go back in the game, showing the replaced rubber bushings.

4f. Finishing Up: EM Oddities
    In this section we'll document some weird stuff that is seen in EM games. Things we haven't really discussed in other parts of this document.

    Bally Relays that use a Lamp Socket.
    On most of the 1970s Bally games, there is a relay on the bottom board called the "delay" relay. Looks like any other relay, except it has a lamp socket and a light bulb. Weird you say? What type of bulb you ask? Well let's talk about this, as the type of bulb used here is important, and the function of this relay (and the "over the top relay", which also used a lamp socket) is interesting.

The delay relay on a Bally Wizard.

    The delay relay does what it says. If the game is turned on, and you manually press the relay plate on the delay relay, the lamp on the socket will turn on, and stay on for a period of time. The bulb used is a #455 flasher bulb. So the bulb will light until the first "flash" is processed by the bulb, then the relay will deactive.

    The delay unit is used when the game is, for example, slam tilted. The coin door has a weighted switch, that when closed, activates the delay relay. This "kills" the power to the game (all coils and lights {except for the coin door lights} go off, punishing a violent coin door kick.) Likewise, on games with over the top feature (Capt. Fantastic), the over-the-top relay will pull in (and sound the game's buzzer) for a short period, until that #455 bulb does it's first "flash."

The over-the-top relay on a Captain Fantastic.

    So what happens if you put a regular #44 or #47 bulb in the delay or over-the-top relays' lamp socket? Well the bulb will immediately blow. And if it doesn't the relay will stay energized forever. So obviously you don't want this. Likewise, if no bulb is installed in the socket, the relay won't "latch" and stay energized for its designed short period of time. Bottom line, use a #455 bulb. So why does a #44 bulb blow? Because the lamp socket is in series with the Delay relay's coil, and connected directly to coil voltage (50 volts.) This works because the current draw on the relay coil buffers the voltage to the #455 bulbs. But in the case of a #44 bulb, it's not enough, and the bulb blows immediately.

    Turn the Game On, Press the Left Flipper Button.
    Another weird thing done on many Bally and Williams EM games during the 1970s is the left flipper "turn on" deal. So a user hits the toggle switch to turn the game on, but the game doesn't come on. Press the cabinet's left flipper button, and the Lock relay energizes, and the game lights up. (Or start a game, and the same thing.) So what's the deal with that?

    I guess Williams and Bally thought that most operators powered games on and didn't actually want them on, until a casual player came by and pressed a flipper button. Potentially this saved power and light bulbs (and the Lock relay.) But today this seems like a silly concept.

    What I do on these games is to disable the function. If you look at the left flipper button switches, there's one that isn't for the flipper, but turns on the Lock relay. I bend this switch permanently closed on my games, so when I hit the power switch, the game lights up and is "on."

Here's a video of these two game oddities, to help explain them.

4g. Finishing Up: Increasing EM Game Performance
    Some will call this blasphemy. They'll complain you'll wear out your playfield. You'll break plastics and drop targets. I call it personal preference or just plain fun making your EM play faster.

    Warning: if you have an EM with drop targets close to the flippers, these upgrades may not be a good idea because of potential breakage (though I've been running them for some time now without any breakages or problems).

    Double Warning: Keeping your playfield CLEAN and WAXED is mandatory for these modifications!

This Williams transformer has two lugs on the right that are normal-tap
(24 volts) and high-tap, from left to right. This game is set to normal tap.
(Williams OXO, 1973.)

Bally transformers are a bit more cryptic. High tap is lug number 2
on the left, and normal tap is lug number 4. This game is set to normal tap.
(Bally Capt. Fantastic, 1976.)

    All the manufacturers have a transformer setting for locations with "low line voltage". Low line voltage happens most often in the summer when your game is plugged into a power line that shares an air conditioner.

    The high-tap transformer setting will bump up the solenoid voltages (only, does not affect light voltages) about 2 or 3 volts. This gives your pop bumpers, kickers, and flippers a bit of extra power. Not a ton, but just a bit. Don't worry, you won't burn out coils with this setting. I set most of my EM games to high-tap and it gives them just a bit more punch. But again, it's personal preference and what you like.

    High-tap does NOT effect the lights. High-tap ONLY effects the solenoid voltages. The 6 volts used for the bulbs aren't effected. They use a separate winding on the transformer. Well, this isn't completely true. If your Gottlieb game has a light feature like "Last Ball In Play", high-tap could roast that particular bulb (only). This happens because some feature lights run off the 30 volt solenoid voltage and use a 75 ohm 10 watt resistor to knock the 30 volt current down for 6 volt lamps. If you go to high-tap, you may need to increase this resistor to 125 ohms. Otherwise those select bulbs (only) will burn too hot. These lamps can be easily seen on Gottlieb schematics. All the normal 6 volt lamps will be on the upper left corner. If a lamp is shown on the shematics in the same section as coils and relays, then there will be a drop-down resistor to limit its lamp current.

This Gottlieb transformer has two lugs on the left
that are the high-tap and normal-tap, from left to right.
This game is set to high-tap. (Gottlieb Jacks Open, 1976.)

    High-Power Flipper Coils.
    High-powered flipper coils for Gottlieb are the "yellow dot" A-5141 coils available from Pinball Resource. They are about 5% to 10% more powerful than the originals. I like these a lot, especially in small 2" flipper Gottlieb games. Some people will argue that you could damage a plastic or drop target. But I've been running these without problem for some time now. On small 2" flipper games, I like them. I like them on long 3" flipper games too. I use these and hi-tap together sometimes, or just hi-tap (game dependant). The high-power flipper coils do give the game a different feel.

    If you have a Williams EM, I wouldn't change the flipper strength. These games (especially the DC powered games) are already pretty strong.

    On Bally games, the general coil for small 2" flippers (including zipper flippers) is AF25-600/31-1000. This is the same power as the coils used on Wizard and other similar games, which is AF25-600/28-800. The next step stronger is the coil used for games like Captain Fantastic, coil# AF25-500/28-1000. So for zipper flipper games, Wizard, etc, I would recommend that as the upgrade. For those concerned about breaking zipper flipper parts with hotter coils, zipper flipper rebuild parts are available. This includes old style and flipper zipper bushings, #C649 ($2.79), the lever arm #A1889-7 (right) and #A1889-8 (left, $10.71). It's a good idea to replace these parts when adding the stronger coils, especially since the original hardware is probably worn to begin with. If using stock zipper flipper coils, be sure to change their metal coil sleeves to new nylon sleeves.

    New Flipper Links and Plungers.
    Flipper links are a fiber material that connects the flipper plunger to the flipper pawl. With time, these wear and the attachment holes elongate. This puts play in the mechanism, which absorbs some power from the flipper. The result is less than powerful flippers.

    Buying new flipper links solves this problem. While you're at it, you might as well get new plungers too. After 25 years or more of use, often they get indentations worn in their sides.

    Also make sure the flipper return spring isn't wound too tight. This can cause additional resistance to the flipper, and make it weaker. Adjust the spring so it has just enough power to return the flipper.

    See flipper rebuilds for more info on making your flippers better.

    New Coil Sleeves.
    Replacing the coil sleeves on all major coils has a big impact on snappy game play. If you didn't replace the flipper coils (which comes with new sleeves), definitely replace the flipper sleeves. It makes an amazing difference in flipper power. Also replace the coil sleeves on the pop bumpers and slingshots. Your game will have much more snap. Don't go too nuts and replace every coil sleeve. Just replace the flipper, pop bumper and slingshot coil sleeves. If your game has metal coil sleeves, these definitely need replacement to new nylon sleeves if possible. Sometimes the metal sleeves will not come out of the coils. In this situation, the entire coil will have to be replaced (which will include a new nylon sleeve). This may not be practical, depending on the game and available/price of new coils.

    On the slingshot kicker or pop bumpers underneath the playfield, you'll need to remove the two screws that hold the coil bracket in place. This will allow you to remove the coil and replace the coil sleeve.

Installing a new coil sleeve on the
slingshot kicker.

    Polish the Pop Bumper Rod and Ring.
    As discussed in the above rebuilding the pop bumpers section, the pop bumper ring needs to be polished. Even new rod and ring assemblies need polished! When rebuilding the pop bumpers, buff the part of the pop bumper metal ring that contacts the ball. It should be as smooth and shiny as a mirror to reduce friction. This allows more of the pop bumper's energy to be transfered to the ball.

    Increase Playfield Slope.
    As simple as this seems, if you increase the angle of your pinball machine, it will play faster! Try moving your two inch rear leg levelers up all the way. Then put your front leg levelers down all the way (or remove them!). If you playfield is clean and waxed, this will increase ball speed dramatically.

    Make sure your Flipper Return Spring is not Over-wound.
    This happens a lot. Unfortunately, sometimes it is done on purpose to try to "fix" a flipper that stays up when the button is released. (On an otherwise clean, adjusted flipper, this kind of sticking occurs because of a magnetized coil stop. The only real cure for this is to replace the coil stop.) With a properly adjusted flipper return spring, there will be only the weakest of return pressure on the flipper linkage. You will know you have it right if the flippers just BARELY swing to their at-rest position when you raise the playfield up. The weight of the flipper bats causes them to be sluggish, which should give you an idea of how weak the return springs really are when properly adjusted.

    Clean and Adjusted EOS & Flipper Cab Switches.
    If the EOS switch or cabinet flipper switch contacts are dirty or pitted, they will have some resistance that will make the flippers weakers. Clean the EOS switch contacts and adjust them. EOS switches should be solidly closed and open about 1/8", only at the very end of flipper travel. When you check EOS adjustment, operate the flipper by pushing the plunger into the coil until it hits the stop. Don't just rotate the flipper bat or push on the linkage because slop in the linkage will keep you from getting an accurate adjustment. After adjustment, be sure that the EOS switches really do open when the flipper is energized. If they stay closed, the flipper coil will burn out. If the flipper still seems really weak, look for cold or broken solder joints on the wires at the EOS switch and where they attach to the coil. While you're at it, clean the flipper button contacts too. Note you should use a metal file for cleaning these switch contacts, since they are tungsten and won't file well with a flexstone.

    Also check the wires going from the flipper coil to the EOS switches. They should be stranded wire, not a solid core wire. If it is solid core (very common on Williams games), replace it with a good quality stranded wire. Solid core wires can easily break internally, making the flippers weak.

    Don't forget to check the cabinet flipper switches too. They take a lot of abuse and need to be filed clean too.

    More Powerful Pop Bumpers and Slingshots.
    You can increase the power of your pop bumpers and slingshots easily by decreasing their coil resistance. The lower the resistance, the more powerful the coil. Increased power means the ball kicks around more and makes the game more lively. To do this, you'll need to remove about 10% to 20% of the coil windings from the coil (don't get greedy and try to remove more than 20%; if you get below 2 ohms the coil will become a "short" and no longer work!) This is very easy, and only takes a few minutes. I do this when I'm replacing the coil sleeve on a pop bumper. Just unwind three "layers" of wire from the coil. This will lower the coil resistance, and make the device stronger. Note you do not usually have to unsolder the coil from the game to do this. Do not do this to flipper coils (did I really need to say that?)

    • Un-wrap the paper wrapping from the coil and save it.
    • Cut the outside coil winding wire from the solder lug (do not cut the inside coil winding wire! You can't unwrap wire from the inside).
    • Un-wrap three layers of wire. A layer is about 40 turns of wire.
    • After the third layer is unwound, leave about two inches of wire and cut off the extra wire.
    • Sand the extra two inch length of wire to remove the painted enamel insulation.
    • Put the two inch wire length through the solder lug hole from which you originally cut the coil winding. Wrap the remainding wire around the solder lug.
    • Put the coil wrapper back on the coil, and secure it with a 1/2 inch piece of electrical tape.
    • Replace the coil (if removed).
    • Solder the wire lug to secure the re-attached coil winding.

    I don't tend to do this modification to the slingshots on games with small flippers. The problem with really strong slingshots is the game gets a lot harder to play! The ball kicks around more, and is much hard to catch in the flippers. Not a problem for long flipper games, but short flipper games become quite difficult to control the ball. But I definitely do this modification to pop bumpers. Good strong pop bumpers makes a game much more lively and fun. Be your own judge. Start with doing the pop bumpers and see how you like it.

Left: Un-wraping the coil winding from the coil. Here we're about half way through the first coil layer.
Right: Three layers of coil windings have now been removed. An extra two inches of wire is left, and sanded clean. Then it's inserted through the (previously cut) solder lug. The remainder will be wrapped around the solder lug, and re-soldered.


    Re-face the Rebound Rubber.
    Ever notice when you plunge the ball how "dead" the upper ball arch's round rebound rubber seems? Even a brand new rebound rubber is hard and dead. But you can re-face these rebound rubbers to give them added bounce and life. This makes the game seem much "snappier" and fun.

    Just stretch a red mini-flipper rubber over the rebound rubber (don't use black mini-flipper rubbers, they are too hard). This will give instant life to an old, dead rebound rubber, or to a new rebound rubber. It is also easier to clean and replace. Mini-flipper rubbers are used on newer games like Twilight Zone and the Addams Family.

A new rebound rubber with an added mini-flipper rubber.

    Playfield Angle.
    If you do the above modifications, you can set your playfield angle fairly steep. I remove the front leg levelers, and set the rear 2" long levelers up all the way. If your playfield is cleaned and waxed, the game plays fast and fun. Maybe this isn't originally how the game play was designed, but I like it.

    If you find the flippers too weak, you may have to decrease the playfield angle. But if you rebuilt the flippers with a new fiber link, plunger and coil sleeve, this shouldn't be a problem.

* Go to the EM Pinball Repair Guide Part 1
* Go to the EM Pinball Repair Guide Part 2
* Go to the Pin Fix-It Index at