System 11A jumpers W16 and W17 depend on the CPU chip brand
From System 11A on, jumpers W16 and W17 ground pin 38 of the 6802/6808 at U24. Install them only when the processor is a Motorola part; with any other brand they must be left open. Check them after replacing the CPU chip.
Systems
Related tips
- System 11A-11C CPU LEDs: normal state
- Which System 11 CPU boards fit which games
- Which System 11 CPU boards swap between generations
- Setting up Leon's System 11 CPU test EPROM
- System 11A-11C diagnostic LED flash codes
- Early System 11 CPU in a later game gives meaningless LED codes
- Checking ground and +5 V on the CPU board
- Running the CPU board on the bench
Source: Repairing Williams System 11 Pinball 1986 to 1990, Deel 1, Clay Harrell (pinrepair.com)