Granny and the Gators
Description: Bally Baby Pacman Bally, 1981, uses Bally -133 MPU board. Bally Baby Pac. A combination of pacman video game and a small pinball playfield. A merge of pacman video and pinball. 7000 Baby Pacs were made. Caveman (Gottlieb System80) and Baby Pac-Man were the first games to combine video games and pinball (Caveman was implemented differently though).
Granny and the Gators followed Baby Pacman and is the same design, but different game play (and not nearly as fun as Baby Pac). Granny used an updated Vidiot board called the "Vidiot Deluxe" board. This used an addition TMS9928 chip (two instead of one on Baby Pacman) and had addition RAM and ROM. Also the boot up flash code sequence is different on the Vidiot Deluxe, due to the additional circuitry.
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Baby Pacman starts off in video game mode. Run around the maze and eat all the dots. There are two outlanes at the bottom of the 13" Wells-Garner monitor, which allow you to escape and play pinball. There are no power pellets in the video game to save you. And the ghosts are all very intelligent, unlike the arcade video game. It is difficult to stay alive in the video game portion (I would sure like a "home ROM" version were I could not die in the video game part). It is entirely possible to lose all your lives (three is the default) in the video game section and never play any pinball. The best playing approach is to get out of the maze as fast as possible. This is done when you go down one of the open tunnels at the bottom. This will put you into the pinball part of the game.
There are a few pinball targets which help unlock power pellets in the video portion. The only way to lose the ball is down the middle drain, which will put you back into the video game, but now the escape tunnels are closed (you are forced to stay in the video mode). The only way to unlock the escape tunnels is to complete the current video screen (eat all the dots). Hopefully you unlocked some power pellets.
Fixing Baby Pacman can be a challenge. But with some simple "break the system down" thinking, it's not too bad. The AS2518-133 MPU board is basically a very slightly modified Bally -35 MPU board. Repair help on that can be found at pinrepair.com/bally. This MPU board controls the pinball functions of Baby Pacman. The "Vidiot" AS-2518-121 board handles the video game portion of the game. These two board must communicate, and this is typically where problems often lie. The Vidiot and MPU board must communicate together or the game will never start-up or work properly. This is probably the biggest problem of fixing a Baby Pacman is communication problems between the MPU and Vidiot boards.
The boards inside a Baby Pacman machine.
MPU Board Battery Corrosion.
Vidiot Board Explained.
The vidiot board also has its own power supply. It uses 12 volts DC unregulated (4 amps) to create +5 volts through two different voltage regulators. One smaller voltage regulator (VR2, 7805) supply 5 volts for the sound section, and the other larger voltage regulator (VR1, LM323) supplies 5 volts for the rest of the board. The unregulated 12 volts is also used for the sound amplifier. In addition 8.2 volts (VR4, 1N5344 5 watt 8.2v Zener diode) is used Video Amp Dematrix. The Baby Pacman Vidiot board does *not* use the +5 volts generated by the lamp/solenoid driver board! The audio amplifier also uses the unregulated 12 volts DC.
There are several test points on the Vidiot board. Check them for the appropriate voltages:
Just like the MPU board, there is a reset section on the Vidiot board. This provides a 100 millisecond wait time for the +5 volts to stablize. This is done by holding the 6809 U8 processor, 6803 U27 processor, and 6821 U7 PIA reset lines low (0 volts) for 100ms. The components for this reset include zener diode VR3 (1N958B or 1N4738a, 7.5 volt) and transistors Q4 (2n4403) and Q5 (2n3904). If the Vidiot board is getting *no* flashes (and the above voltages check out and the LED is good), check the reset lines on the processors to see if it is high. Use a DMM and check for 4.5 volts at U8 pin 37 (6809), U27 pin 6 (6803), and U7 pin 34 (6821 PIA). If all are zero volts, the reset circuit is not working (all three chips should have their reset either high or low, if you have a mixed bag, there is a broken trace). If reset is low, check Q4 and Q5 and VR3. If the voltage is 4.5 volts, then I would next suspect an EPROM as bad (or a broken trace going to the EPROMs), or possibly the clock circuit (check 6803 U27 pin 10 for a clock signal using an oscope). I believe the Vidiot board initially boots from the EPROM at U29, so check that EPROM first.
Lastly the Vidiot board has a video game section, broken into sub-sections. One sub-secton includes the 6809 video game processor at U27, the address decoder, and the program RAM/ROM. The communications interface forms another sub-section. The last sub-section is the video display processor (TMS9928 at U16), video RAM, and video amp dematrix.
The communications interface consists of U1,U2 (74LS374), U3,U4 (4050), U6 (743684), and U7 (6821 PIA). These chips work with the 6809 processor at U8 to provide MPU-to-Vidiot communications, vidiot switch reading, and video-sound processor communications. The vidiot has its own switch matrix of four strobes by eight returns (28 switches total).
The video display process at U16 is a TMS9928 40 pin chip. This processes all video, control and sync signals, and storage/retreival of data from the dynamic screen memory (VRAM at U19-U26). It can output 15 colors and 32 objects (sprites) with a minimum of programming overhead. The 6809 at U8 communicates with the TMS9928 to accomplish this. The video amp dematrix converts the video signals to Red/Green/Blue and Sync for the color 13" monitor.
The sound section of the Vidiot board has two sub-sections. The sound 6803 microprocess at U27, its bus demultiplexor, address decoder and program ROM form one sub-section. The EPROMs at U29 and U30 are the sound EPROMs (but only U29 2764 is used for Baby Pacman). The D-A (digital-analog) converter, low pass filter and power amplifier form the other sub-section.
No Video or Bad Video.
The TMS9928 chip outputs the video signals directly to two video amplifiers, LM359N at U18 and U17, and then goes to the output video plug at J4. If either or both LM359N chips are bad, you will either get absolutely no video, or video that won't sync. These video amplifier chips do fail (just repaired a Vidiot board where the TMS9928 was fine, but both U17 and U18 LM359N chips were bad).
Also note the video signal passes thru a number of resistors around the LM359N video amplifiers. If the colors are strange or won't sync, check these resistors. In particular there are three 100 ohm 1/2 watt resistors than often go open (R89, R97, R102). You will have to remove one end of the resistor from the board to test with a DMM. Also the three 3.9k resistors (R101, R96, R88) mounted just above the 100 ohm resistors should be checked too.
The pots for the colors and sync also go bad often. The green and sync are 10k ohms, and the red and blue are 2.5k ohm pots. Replacement is a good idea.
Video ground is another problem. There is a large ground plane on the front and back side of the Vidiot board. Make sure these two ground planes "buzz out" and have continuity with each other (a small jumper may be required to ensure this). Also if the video is over-saturated with blue or red, there may be a problem with the video signal ground at J4 pin 2. The factory often has a capacitor going from Vidiot J4 pin 2 to ground. If red and/or blue are over-saturated, replace this resistor with a jumper from J4 pin 2 to ground. This should fix the saturation problem.
Also check the two 74LS374 chips at U1 and U2 as these are problematic too, though this may not reflect directly in the video signal.
Vidiot TMS9928 Heat Problems (Heat Sink).
The easiest heat sink to use is a 40 pin DIP slide-on black anodized heat sink. DigiKey sells a slide-on version, part number HS183-ND, which dissipates 1 watt of heat. They also sell a glue-on version, part number HS274-ND, which dissipates 2.5 watts of heat.
Here a proper Communications Test screen in a working Baby Pacman.
Vidiot Test Button SW1.
Remember if pressing Vidiot SW1 once brought the communications test up, pressing SW1 a second time will bring the color bar test up.
Note the MPU (S33) test button is not helpful for diagnostics.
Vidiot Test Button SW2.
Tilts Causing Problems.
Testing the Vidiot Board "on the bench".
VJ4 - Video (optional, 12 pin .156" molex connector):
VJ5 - Speaker (optional, 2 pin .156" molex connector):
Be sure to check the power voltages with your work bench test rig: Use the test points on the Vidiot board.
With power connected, the Vidiot board should flash ten times (flash codes are shown below), and the studder/abbreviated Pacman tune should play during bootup (assuming a speaker is connected to J5). After the ten flashes, pressing SW1 will bring up the either the Communications test (with no Xmit/Rec info), or the color bar test. If the Communications test comes up, press SW1 again for the color bar test. Of course both of these test are useless unless there is a video monitor connected. Pressing SW2 will play a short electronic space sound and the LED will flash two times.
At this point you can take this one step further and build a harness that will connect the Vidiot board to a -35 (or -133) MPU board. I have a Bally test fixture that I made, which runs a -35 (or -17) MPU board through a standard AS2518-18 power supply and a AS2518-22 (or AS2518-17) solenoid driver board. I can put Baby Pacman U2 and U6 2732 EPROMs in the -35 MPU board, disconnect the Bally lamp driver board and connect the Vidiot board VJ1 connector to the MPU board's J1 and J2 connectors. I connect a video monitor to the Vidiot board's VJ4 connector and boot up the test fixture. Baby Pacman will boot and go into attract mode on the video monitor. Pressing the standard Bally coin door switches I can add credits, start a game or go into diagnostics. If I have a joystick connected to the Vidiot VJ2 connector, I can play Baby Pacman on the test fixture! I just can't play the pinball part (no playfield).
All the diagnostic tests will run except for the Lamp test. This including the solenoid test running through a pinball AS2518-22 or -17 solenoid driver board. The communications test will also run correctly showing the proper communications between the Vidiot and MPU boards (assuming the harness made is wired correctly). Note I am *not* using a -133 MPU board on my test fixture. Since my fixture provides 43 volts DC to MPU J4 pin 15, connecting a -133 would damage the MPU board ( the -133 MPU expects 6 volts AC at J4 pin 15). This "zero cross" circuit is used for the CPU controlled lamps on Baby Pacman. In fact, they use one 2N5060 SCR to control two different lamps, depending on the phase of the zero crossing (this was also done on the Bally 6803 system).
Here is the connector harness needed to make the communications test work between the MPU and Vidiot board:
# This single VJ1 pin goes to TWO mpu board connector pins.
If you would like to hook up a joystick to the Vidiot board, here's the pinout for that:
Coin Door Red Button Diagnostic Tests.
Power-On Sequence and LED Flash Codes.
Also the game plays a sick-sounding short pacman tune at power-on. Then the game goes into "attract mode" with the pacman-ish attract mode screen on the 13" video monitor. If either the MPU or Vidiot board's LEDs do not flash the appropriate amount of times, the game will never start. If there is a communications problem between the MPU and Vidiot boards the game will never start.
Baby Pac DIP Switches.
Specials are set using the game's red button inside the coin door. Special Options=02 will award a "Play Again" (extra man). 03=reward a replay, 01=novelty (points), 00=no award.
High score to date function is also set using the game's red button inside the coin door. Hi-Score set to 02 or 03 will award a "play again" (extra man), 01=50k points, 00=no award.
Baby Pacman Rectifier and Lamp/Solenoid Driver boards.
The AS-2518-107 lamp/solenoid driver board often has problems. Most often the 2N5060 SCRs fail causing non-working or locked-on pinball playfield lamps. The 4514 lamp decoders (U1,U2) usually don't fail though. So if some playfield lamps don't work (and its not the bulb or lamp socket), suspect a 2N5060 SCR on the lamp/solenoid driver board connector. Note the color of the wire going to the problem lamp socket. Then find this wire color on the lamp/solenoid driver board connector. Then trace the connector its corresponding 2N5060 SCR. The lower leg of the SCR can be grounded, and the playfield light should turn on. If it does the wiring from the SCR to the playfield lamp is good, and the 2N5060 SCR should be replaced.
Also the SE9302 transistors (TIP102 replaceable) and CA3081 pre-driver (U3,U5) chips can fail causing locked-on or non-working solenoids. The solenoid drivers are decoded by a 74LS138 chip at U4. Also on this board is the +5 volt voltage regulator at Q41 and a 11,000 mfd filter capacitor at C2. This supplies power to the -133 MPU board. Often the C2 filter capacitor needs to be replaced.
Here's a list of the TIP102 (SE9302) transistors on the solenoid driver board and what they control. Listed in physical order from top down.
Baby Pac Playfield Switches.
Baby Pacman Vidiot Board LED Flashes.
After the 6803 CPU chip at U27 resets properly (using a 100 millisecond wait for the 5 volts to stablize), the sound 6803 CPU chip (U27) attempts to test the 2764 sound EPROM at U29. If the chksum from the U29 sound EPROM is good, the first flash is shown. If there is no first LED flash, usually the sound EPROM at U29 is bad.
The Vidiot Sound section test is now complete. The rest of the LED flashes pertain to the video game portion of the Vidiot board.
Granny and the Gators.
The boards inside a Granny and the Gators. Notice they are
Granny and the Gators also uses a Bally "Cheap Squeek" sound board. Because of this, the first two LED flashes on the Vidiot board reflect this usage. In a normal working Granny and the Gators there are a total of 14 LED boot up flashes. But if you are booting a Vidiot Deluxe board on the work bench without the Cheap Squeek board, the Vidiot boot up LED squence starts at flash #3.
The ROM code for Granny and the Gators' MPU and Vidiot and cheap squeak boards is available here.
Granny and the Gators (and Baby Pac) MPU on the bench.
After either G&G or Baby Pacman is booted on the test fixture, press the "test" button once, and the MPU will seemingly go "dead". But what it's actually doing is showing the communications screen (which you obviously can't see with regular pinball score displays!) Press "test" one more times, and the -133 goes to lamp test. On a regular Bally test fixture, all 40 controlled lamps will flash off and on (but at a slightly different speed compared to a -35 board.) Press "test" one more time, and the coil test will start. For Granny and the Gators, there's only four coils (and the flipper relay).
A common failure point for the Vidiot boards is the TMS9928 chip. Baby Pac uses one, Granny & Gators uses two of these. On Granny, if the game seemingly boots with all it's LED flashes (both MPU and Vidiot), yet the game screen is blank and a few playfield lights are flashing on and off, this is probably a bad TMS9928 chip.
On Granny and the Gators' -133 MPU flicker and six LED flashes, note that flash number two (the 5101 RAM test) is longer coming that say a normal -35 board. Don't be alarmed by this, it is normal.
Vidiot Deluxe board as used in Granny and the Gators.
Vidiot Deluxe board's RAM and two TMS9928 (with added heat sink/fan).
Granny and Gators' Vidiot Deluxe LED Codes.
A prototype Baby Pacman. This smaller sit-down format was apparently how
"baby pacman" got its name (the standup production format really doesn't
look like a 'baby', but this sit-down version does). They only made a few
of these before changing their minds and going to the standup format.
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