The credit button stops working, and in switch test every switch in that row of the matrix is dead.
Credit button and a whole switch row dead: shorted diode on one switch
Cause: The diode on the credit button switch had failed, dragging down the whole row.
Checks
- With switch test running, unplug the switch matrix plugs at the CPU board (1J8 and 1J10) and jumper row and column pins with clip leads; if every position registers, the board is fine and the fault is in the wiring or switches.
- Check the diode on each switch in the dead row, starting with the one that failed first.
Fix
- Replace the faulty diode or the whole switch.
Systems
Games
Related tips
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Source: Pinball Repair help group!! (Facebook group)