Two of the three pop bumpers would not fire when the ball hit the skirt, although they fired in coil test; the bumpers also triggered on their own when the flippers were used.
Pop bumpers won't fire from the skirt, or fire by themselves: bad switch capacitors
Cause: The small capacitors fitted across the pop bumper switches had failed, so the game saw a bumper switch as constantly closed, which upsets the switch matrix and the other bumpers.
Checks
- In switch test, look for a pop bumper switch that shows closed with nothing touching it.
- Check the bumper switch gaps and the switch wiring and connectors for cracked solder.
Fix
- Clip or desolder one leg of the capacitor on the affected bumper switches to confirm, then replace the capacitors with new ones of the same value.
Games
Related tips
- Pop bumpers fire nonstop after a solenoid expander swap: board jumper set wrong
- Bonus multiplier advances on bumper hits: hair-trigger mushroom switch
- Changing to 3-ball play: DIP switches 31 and 32
Source: Pinball Repair help group!! (Facebook group)