At power-up from cold the game reports ground shorts on switch rows 2 and 3 and a bad Idol switch. The errors clear after a few minutes, or when something on the row is touched, and don't come back on a warm restart.
Ground short rows 2 and 3 and Idol switch error on a cold start: failing 10-opto board
Cause: The 10-opto board was failing in a temperature-sensitive way.
Checks
- Unplug the playfield switch connectors: if the shorts disappear, the fault is on the playfield side.
- Check every diode and opto on rows 2 and 3.
- Inspect the opto board's capacitor and solder pads for corrosion and resolder it; if the fault remains, try another opto board.
Fix
- Replace the 10-opto board.
Systems
Games
Related tips
- Every opto dead and opto board LED off: check the J118 ground
- Idol optos missing from switch test: use idol test, then fix connectors
- Indiana Jones to Demolition Man games have two LM339 opto boards
- Confused switch matrix from LM339s on opto boards
- How WPC opto switches work and which half fails
- Opto switches dead or intermittent: check the 12 volt supplies
- All optos dead: lost opto ground connection
- Phantom or erratic switches traced to an opto driver board
Source: Pinball Repair help group!! (Facebook group)