Now and then during a game the solenoids act up: they go very weak or the wrong coil fires, then everything returns to normal. Coil test also shows odd results.
Coils go weak or the wrong coil fires mid-game: reseat the solenoid driver plugs
Cause: A poor connection at the solenoid driver board connectors, most likely the one carrying the solenoid data lines from the MPU. Here it happened with a new replacement driver board.
Checks
- Reseat every connector on the solenoid driver board and see if the fault stops.
- Inspect the header pins on both the MPU and the driver board for cracked solder joints.
- Check the female connector pins for wear or a loose wire.
Fix
- Reseat the connectors; for a lasting fix, repin the solenoid data connector and reflow its header pins.
Systems
Games
Related tips
- 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
- MPU gives 3 flashes after reassembly: two 15-pin plugs swapped
- Saucer fires at power-on and blows the playfield fuse: wrong coil killed its transistor
- Coil in the drop target assembly is always on: burnt trace on the solenoid driver board
- No +5V on any board and no MPU LED: bad return pin in the solenoid driver board J3 plug
- Top lane gate never opens, even in solenoid test: failed driver transistor
- Pop bumpers fire nonstop after a solenoid expander swap: board jumper set wrong
Source: Pinball Repair help group!! (Facebook group)