With the ball launcher coil plugged in, power-up blows fuse F21 and takes out the coil's driver transistor (Q2) and diode, every time. With the coil unplugged everything else works. New coils, diodes and transistors didn't help.

Ball launcher blows its fuse, driver and diode at power-up: coil lug touching bracket

Cause: A home-made coil mounting bracket let the coil twist with vibration until one coil lug touched the bracket and shorted to ground.

Checks

• Check the coil wiring isn't reversed (that blows the transistor and diode at once).
• Look at how the coil sits in its bracket: can either lug touch metal if the coil rotates?
• Check each coil wire for a short to ground.

Fix

• Make sure the coil can't turn in its bracket and that the lugs clear all metal (here the square bracket corners were ground round); then replace the fuse, transistor and diode.

Systems

• Sega/Stern Whitestar

Games

• Goldeneye

Related tips

• Left flipper MOSFET keeps shorting after a few flips: counterfeit replacement transistors
• Trough upkicker blows F6 and cooks a new coil: its diode was the other way round

Source: Pinball Repair help group!! (Facebook group)