Check the coil diode after replacing a driver
A coil with a bad diode can kill a new driver transistor almost at once. After replacing a driver, check the diode on that coil (and the others): give each a gentle tug to find cracked bodies or leads.
Systems
Related tips
- Which way a coil diode goes
- Testing the diode on a coil
- Check the wire from the coil to its driver transistor
- Coil diode polarity
- Testing a coil, switch or flipper diode with a meter
- New coil's diode faces the other way: keep each wire on the same diode end
- Test a 1N400x diode on a coil, lamp socket or switch
- A cracked coil diode keeps killing its driver transistor
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)