Usual causes of lock-ups and resets
In rough order: the 40-pin CPU/driver interboard connector, the original Scanbe chip sockets on the boards, cracked header pin solder joints on board connectors, the CPU board 1J2 power connector, the +5 V filter capacitor, the bridge rectifier (System 7), missing or broken coil diodes, and switch matrix faults.
Systems
Related tips
- System 3 CPU board reset circuit modification
- Random lockups from the 12 V logic pin
- Game keeps resetting: replace the 5101 RAM (an NVRAM works)
- CPU never starts: check the reset line at IC1 pin 40
- Intermittent lockups with both CPU LEDs on
- Free play won't take on System 7: do a factory reset first
- Game only boots after several power cycles: corrosion under the 6808 CPU socket
- "Adjust Failure" at power-on
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)