CPU-controlled and special solenoids
Coils 1 to 16 are CPU-controlled: PIA IC5 drives them through a 7408 gate, a 2N4401 and a TIP120/TIP102, and they fire once even if their switch sticks. The six special solenoids (pop bumpers and slingshots, 17-22 in the test) are fired directly by their playfield trigger switches through TTL logic, without the CPU, for speed. Their trigger switches are outside the switch matrix; a second switch on each device, which is in the matrix, closes as the coil pulls in and tells the CPU to score it.
Systems
Related tips
- Special solenoid trigger test at 2J12/2J13
- Pop or sling works in the game but not in test, or the reverse
- Solenoid driver test at 2J9 and 2J11 with Leon's code
- A cracked coil diode keeps killing its driver transistor
- Coil outputs available on System 3-7
- The coin lockout coil is meant to be on
- Special solenoid control paths
- Pop bumper or slingshot locked on
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)