Special solenoid control paths
Specials 1-6 (test numbers 17-22) are switched in test by the CA2/CB2 lines (pins 19 and 39) of four different PIAs: 1 by lamp PIA IC10 pin 19, 2 by IC10 pin 39, 3 by switch PIA IC11 pin 19, 4 by IC11 pin 39 (all driver board), 5 by solenoid PIA IC5 pin 39, and 6 by display PIA IC18 pin 19 on the CPU board. Gate pins (7408 in/out, then 7402 in/out): 1 IC6 1/3, IC9 2/1; 2 IC6 10/8, IC8 12/13; 3 IC6 13/11, IC8 5/4; 4 IC6 4/6, IC8 9/10; 5 IC7 13/11, IC9 5/4; 6 IC7 10/8, IC9 12/13. 2N4401 pre-driver and TIP120/TIP102 driver pairs are Q1/Q2, Q3/Q4, Q5/Q6, Q7/Q8, Q9/Q10 and Q11/Q12.
Systems
Related tips
- Why the solenoid and switch PIAs fail most
- Test a TIP120/TIP102 solenoid driver with a meter
- Slings and pops all burned at once: CPU lock-up from the 40-pin interconnect
- Solenoid fuse blows at power-on and solenoids fire: driver board logic chips
- Kicker coil locks on again after a new TIP122: dead 7408 gate on the driver board
- Slings and pop bumpers feel sluggish: backbox boards loose with missing mounting screws
- System 6 and System 7 driver boards can be swapped for testing
- Coil locks on and new transistors don't help: a failed 7408 on the driver board
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)