Coil-mounted diodes: replace rather than test
Diodes mounted on the coils are the ones that break, usually visibly. Testing one means cutting a lead anyway, so if you suspect it, cut it off and fit a new 1N4004. Board-mounted diodes on the auxiliary power driver board rarely fail.
Systems
Related tips
- Testing the diode on a coil
- Testing a coil diode
- Which way a coil diode goes
- Which way a coil diode goes
- What the coil diode does and how a bad one shows up
- Testing a coil diode on the driver board
- Testing the diodes on a flipper coil
- Coil diode and wire orientation when replacing a coil
Source: Repairing Williams System 11 Pinball 1986 to 1990, Deel 1, Clay Harrell (pinrepair.com)