Solenoid select lines: MPU PIA U11 to SDB 74154 pin map
PB0: PIA pin 10 on U11, R97 (470 ohm), MPU J4-4, SDB J4-6, U2 pin 23. PB1: pin 11, R98, J4-3, SDB J4-5, U2 pin 22. PB2: pin 12, R99, J4-2, SDB J4-4, U2 pin 21. PB3: pin 13, R100, J4-1, SDB J4-3, U2 pin 20. CB2 bank select: pin 19, R106 (470 ohm), J4-10, SDB J4-7, U2 pin 19. The continuous lines PB4-PB7 (pins 14-17, R101/R102/R104/R105, 330 ohm, MPU J4-5 to J4-8, SDB J4-11, 9, 8, 10) skip the decoder and drive the lockout coil, flipper enable and similar coils directly.
Systems
Related tips
- Solenoid selection: four MPU lines decoded by a 74154
- Test the coils behind the solenoid expander
- No coils work at all
- Solenoids fire out of order in solenoid test
- Find a shorted coil circuit by plugging SDB connectors one at a time
- Coil locks on at power-up or stays on
- How Bally coils are switched
- Flippers and some coils work, others are dead
Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)