After fitting new flipper assemblies, one flipper does nothing and blows its flipper fuse when pressed. The wires had been moved over in the same positions as on the old coil.
New flipper assembly won't fire and blows its fuse: coil wired by habit, diode blown
Cause: The new coil's diode faced the opposite way to the old one, so wiring it the same way as before put the supply across the diode in its forward direction, which destroyed the diode. The coil then measured about 0.3 ohms instead of about 3 ohms.
Checks
- Before moving wires over, compare the diode direction (banded end) on the old and new coils: the supply wire goes to the banded end.
- Measure the coil across its lugs and compare with the working side; a near-zero reading points to a shorted diode.
- Test the flipper's drive transistor too.
Fix
- Replace the blown diode (or the coil) and connect the supply to the banded side of the diode.
Systems
Games
Related tips
- Flipper works only some of the time: clean the button leaf switch
- Left flipper MOSFET keeps shorting after a few flips: counterfeit replacement transistors
Source: Pinball Repair help group!! (Facebook group)