The game plays normally, but after switching off it only sometimes keeps its high scores and credits. Batteries are good, mounted remotely, and there is no sign of corrosion.
Scores and credits sometimes lost at power-off, batteries good: failing 5101 RAM
Cause: The 5101 memory chip on the MPU that holds the settings while the game is off was failing intermittently.
Checks
- Check the battery backup voltage reaches the MPU memory circuit with the game off, and look for corrosion near the battery pads and the parts around them.
- Repin or reseat the MPU connectors to rule out an intermittent connection.
- If the backup supply is good and memory is still lost now and then, suspect the 5101 itself.
Fix
- Replace the 5101 with a 5101-compatible NVRAM, which keeps settings without batteries.
Systems
Games
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Source: Pinball Repair help group!! (Facebook group)