The game asks for opto 41 to be adjusted at power-up, the mystery wheel spins only briefly or not at all from the Spook House, and it awards random prizes. The wheel test shows an error count.
Mystery wheel opto 41 error and random awards: loose wire at MPU connector 1J8
Cause: A wire had come loose at connector 1J8 on the MPU board. The mystery wheel opto is the only switch in its matrix column, so the rest of the game works normally.
Checks
- In the switch levels test, see whether the wheel opto changes state when the wheel tab blocks it.
- Unplug the switch connectors at the MPU and test the column directly to tell the board from the wiring.
- Check the wires and pins at 1J8 for one that is loose or broken.
- Also check the wheel disk is tight on its shaft and runs square so its tab passes through the opto.
Fix
- Repair or repin the loose wire at 1J8.
Systems
Games
Related tips
- Playfield switches fire coils and switch columns misread: failed column driver Q44
- "Checksum Error" at power-on
- Connector 1J8 switch column pins
- "Adjust Failure" at power-on
- "IRQ Failure" at power-on
- Won't boot after restoration, new EPROMs fitted: try the original ROMs
- Resets continue after diode repair: power and connector checks
- Displays flash bright and speakers noisy, game does nothing
Source: Pinball Repair help group!! (Facebook group)