The right pop bumper stopped working because a wire had come out of J127. After refitting the wire, the coil locked on at power-up and burned.

Pop bumper locks on and burns its coil after a loose wire is refitted: shorted Q48

Cause: The pop bumper's driver transistor Q48 had failed shorted.

Checks

• Before reconnecting a dead coil, test its driver transistor (and pre-driver) in diode mode.
• Repin or replace the IDC connector that let the wire come out.

Fix

• Replace Q48 (and check its pre-driver), then refit the coil.

Systems

• WPC Fliptronics

Games

• Twilight Zone

Related tips

• No coils, lamps, GI or flashers but display and sound work: check blanking
• Solenoid numbers above 28 and the 8-driver auxiliary board
• Saucer coil locks on and kills its TIP102 each time: bad diode on the board
• Burned power driver board traces at the header feeding AC to the Fliptronic board
• 20-second test for shorted coil driver transistors

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