In the middle of a game every coil stops firing while switches still score. After a power cycle the coils work again for a few flipper presses, then die again; in solenoid test nothing fires and only the flipper relay clicks.
All coils die after a few flipper presses: bad joint on the coil power chain
Cause: The coil power wire is daisy-chained between the lower flippers, the under-playfield fuse and the upper flipper. A poor solder joint where the wires met at the upper flipper coil lug was losing contact under vibration.
Checks
- When the coils stop, measure coil voltage at a coil lug, then at the rectifier board's coil supply test point, to see whether power or the drive side is missing.
- Check the under-playfield fuse holder and fuse for continuity, since that fuse sits in the same chain.
- Inspect every joint on the power wire chain, especially lugs with several wires soldered together.
Fix
- Resolder the wires firmly onto the lug where the joint is poor (here the three wires on the upper flipper lug).
Systems
Games
Related tips
- One coil dead with a good transistor and power at the coil
- Top saucer never kicks but fires when its transistor is grounded: rebuild J4
- Knocker fires instead of the outhole kicker: bad solenoid driver J4 connector
- Flickering displays and flipper drop-outs from a poor backbox ground
- Check the wire from a coil back to the solenoid driver board
Source: Pinball Repair help group!! (Facebook group)