After an earlier switch wiring mistake (which had killed the CPU board), one switch triggers several others, the left flipper switch shows open, and the right flipper also fires the cannon. Unplugging the small ribbon between the CPU and power driver board makes the playfield switches read normally.
One switch triggers others and flippers act oddly: drop target switch wired backwards
Cause: A drop target switch had been rewired backwards, with its white wires on the far blade instead of the near one, tying parts of the matrix and the flipper opto circuit together.
Checks
- Compare the wiring on recently worked switches with the manual or a photo, wire colour by wire colour.
- Unplug the CPU to power driver ribbon to separate matrix faults from flipper opto faults.
Fix
- Put the switch wires back on the correct blades and retest the matrix.
Systems
Games
Related tips
- Several solenoids and a lamp group dead: reseat the CPU-to-driver ribbon
- No playfield switches work: check the regulated 12 V
- Row or column "ground short" errors
- Random coil firing or slam tilt from weak 12 V (notably Theatre of Magic)
- Launch coil locks on and blows its transistor and fuse every time it is tested
- Game accepts no coins and will not start
- Driver board LED1 off: switch matrix 12 V missing (WPC-S and earlier)
- Resets from worn power connectors between transformer, driver and CPU boards
Source: Pinball Repair help group!! (Facebook group)