When the game is switched on all the flippers activate and the 50 V fuse on the driver board blows. Switch test shows many switches with ground shorts, and with the high voltage fuses out two back flashers still lock on when the coin door is closed.
All flippers fire at power-up and blow the 50 V fuse: aux board ribbon upside down
Cause: The ribbon cable from the CPU board to the auxiliary driver board had been plugged in upside down at the CPU end.
Checks
- Before blaming boards, check every ribbon cable is fitted the right way round (pin 1 to pin 1) at both ends.
- Note any coil or flasher that turns on with only the low voltage fuses fitted: it points to a wiring or ribbon mistake.
Fix
- Refit the auxiliary driver board ribbon cable the right way round.
Systems
Games
Related tips
- Every coil and flasher locks on after reassembly: aux driver ribbon cable reversed
- DMD shows a few dots and a coil fuse blows after reseating boards: ribbon off one row
- Resets from worn power connectors between transformer, driver and CPU boards
- STNG: under-playfield diverter coils lock on during play
- CPU board switch connectors
- Solenoid numbers above 28 and the 8-driver auxiliary board
- Reseat the ribbon cables before chasing odd behavior
- Replacement .100" Molex parts for the CPU switch connectors
Source: Pinball Repair help group!! (Facebook group)