Coils 9-15 and coin lockout: connector, transistors, PIA pin
Driver is the TIP120 (fit a TIP102), pre-driver the 2N4401, gate a 7408 whose two inputs are the PIA line and blanking; the PIA outputs read low in attract mode. Coil 9: J9-9; driver Q31, pre-driver Q30; gate IC3 out 8, in 10/9; PIA IC5-10. Coil 10: J9-7; driver Q33, pre-driver Q32; gate IC3 out 11, in 12/13; PIA IC5-11. Coil 11: J9-1; driver Q35, pre-driver Q34; gate IC3 out 6, in 4/5; PIA IC5-12. Coil 12: J9-2; driver Q37, pre-driver Q36; gate IC3 out 3, in 1/2; PIA IC5-13. Coil 13: J9-3; driver Q39, pre-driver Q38; gate IC4 out 8, in 10/9; PIA IC5-14. Coil 14: J9-4; driver Q41, pre-driver Q40; gate IC4 out 11, in 12/13; PIA IC5-15. Coil 15: J9-5; driver Q43, pre-driver Q42; gate IC4 out 6, in 4/5; PIA IC5-16. Coil 16 (coin lockout): J9-6; driver Q45, pre-driver Q44; gate IC4 out 3, in 1/2; PIA IC5-17. The lockout PIA output reads high unless the game is at its credit limit.
Systems
Related tips
- A low resistance coil points to a bad driver transistor
- Coil still locked on with good transistors and gate
- Coil locks on and new transistors don't help: a failed 7408 on the driver board
- What each 6821 PIA does
- How a coil is switched on
- Slings and pops all burned at once: CPU lock-up from the 40-pin interconnect
- Driver board transistors and what they drive
- Why the solenoid and switch PIAs fail most
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)