In switch test, pressing the right flipper also shows the two opto switches closing. Unplugging the flipper switch board stops it, but then the flippers can't be used to scroll menus.
Pressing a flipper also triggers the opto switches: bad diode and botched ground repair
Cause: A failed diode on a lamp socket, plus a poor earlier repair to a ground connection, was feeding back into the switch matrix.
Checks
- Note which switches show up together in switch test and follow their shared rows and columns.
- Check the diodes on lamps and switches along that path, and inspect any ground wires that have been repaired or spliced.
Fix
- Replace the bad lamp socket and its diode, and redo the faulty ground repair properly.
Systems
Games
Related tips
- Closing one switch shows several in the same column
- Switch diodes are on the A17 board, not the switches
- Using the flippers scores points: a target switch closed by vibration
Source: Pinball Repair help group!! (Facebook group)