Test a 1N400x diode on a coil, lamp socket or switch
Steps
- Switch off the game.
- Free one lead of the diode by cutting or unsoldering it so it is out of circuit (diodes on circuit boards can usually be tested in place).
- Meter on diode test. Black lead on the banded end, red on the other end: expect about 0.4 to 0.6 V.
- Swap the leads: expect no reading (open).
- Replace with a 1N4004 if either reading is wrong.
Systems
Related tips
- Testing a coil, switch or flipper diode with a meter
- Which way a coil diode goes
- Testing the diode on a coil
- Test a lamp socket diode in place
- Spare diodes for coils and switches
- Lamp diodes sit on small boards at each socket
- Diode orientation on #44/47 lamp sockets, and 555 sockets
- Testing a coil diode
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Two, Clay Harrell (pinrepair.com)