Other quick PIA checks: swap or touch test
Move a suspect PIA, with the power off, into the same position on a working board to see if it breaks that board. Or disconnect all but the power connector, run the board, and carefully touch each PIA and the U25 RAM: a warm chip is suspect, as is a dark ring on its top.
Systems
Related tips
- What each 6821 PIA on the CPU board controls
- Checking PIA outputs with the test EPROM running
- Which System 11 CPU boards swap between generations
- Find out how the board died: failures cascade to the PIAs
- Leon test EPROM does not run: check the 6808 and its pins
- Wrong coils fire and drop target dead: bad PIAs, shorted coil diode and Q14
- System 11 CPU board won't boot after cleaning: worn ROM socket contacts
- System 11 NVRAM upgrade not working: fit it at U25, not U23 (sound RAM)
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)