Game EPROMs with missing window labels may be erased
The game EPROMs at U26 and U27 hold the boot code. If the label over a chip's quartz window has fallen off, light may have erased it; have it reprogrammed or test with a test EPROM.
Systems
Related tips
- Using the Williams System 11 test fixture EPROM
- Checking PIA outputs with the test EPROM running
- Testing U25 RAM with Leon's EPROM
- Setting up Leon's System 11 CPU test EPROM
- Leon test EPROM does not run: check the 6808 and its pins
- 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)
- Right sling locks on at power-up and a pop is dead: bad 7402 at U45
Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Two, Clay Harrell (pinrepair.com)