Baby Pac-Man solenoid board select lines
Here just three lines, PB0-PB2, are encoded, PB4-PB6 are continuous, and PB3 and PB7 are not used. On its SDB, J9 pins 7, 6, 5 carry PB0-PB2, J9 pin 4 carries CB2, and J4 pins 10, 9, 8 carry PB4-PB6. Decoding is done by a 74LS138 at U4.
Systems
Games
Related tips
- Solenoid selection: four MPU lines decoded by a 74154
- Test the coils behind the solenoid expander
- No coils work at all
- Wrong coil fires or a coil never fires
- How Bally coils are switched
- Flippers and some coils work, others are dead
- Find a shorted coil circuit by plugging SDB connectors one at a time
- Skip the driver board mods on Baby Pac-Man
Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)