The top saucer (solenoid 18) will not fire in play or in solenoid test, though the saucer switch works. Grounding the driver transistor tab fires the coil, and swapping in another solenoid driver board doesn't help.
Top saucer never kicks but fires when its transistor is grounded: rebuild J4
Cause: A bad contact in the J4 connector on the solenoid driver board.
Checks
- Ground the transistor tab briefly to prove the coil and its wiring work.
- If a second driver board shows the same fault, look at the connectors rather than the board.
Fix
- Replace the J4 housing and repin it with new crimp pins.
Systems
Games
Related tips
- One coil dead with a good transistor and power at the coil
- Check the wire from a coil back to the solenoid driver board
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- Coils go weak or the wrong coil fires mid-game: reseat the solenoid driver plugs
- All coils die after a few flipper presses: bad joint on the coil power chain
- Pop bumpers, slings and post weak, flippers fine: bad coil ground return plug
- Knocker fires instead of the outhole kicker: bad solenoid driver J4 connector
- Solenoid driver board J3 pin functions
Source: Pinball Repair help group!! (Facebook group)