The right kicker (special solenoid Q12) works for a while, then locks on and burns out its transistor; new transistors keep failing. The coil reads a normal 4 ohms.
Right kicker keeps killing its driver transistor: shorted resistor network
Cause: The resistor network on the special solenoid switch inputs (including the unused inputs) had shorted, so the circuit could be turned on without the kicker switch.
Checks
- Check the coil diode out of circuit (clip one leg) and that it is wired with the band on the power side.
- Make sure the coil lugs cannot touch the mounting bracket and that the kicker switch is not sticking closed.
- Check the predriver transistors and the 7402/7407 logic for that circuit.
- Measure the resistor network on the special solenoid switch inputs for shorted elements.
Fix
- Replace the shorted resistor network, then fit a new driver transistor for the kicker.
Games
Source: Pinball Repair help group!! (Facebook group)