A pop bumper fires with no ball near it, or works intermittently.
Pop bumpers fire on their own or work only sometimes
Cause: The pop bumper driver boards get their logic ground through a single pin of the CPU board; if it is intermittent, the pops misbehave.
Fix
- Add a second ground path from the pop bumper boards to the reinforced backbox ground.
Systems
Related tips
- A pop bumper doesn't work at all
- Pop bumper fires erratically or several times
- How the pop bumper driver board fires its coil
- A pop bumper never fires
- Add power and fire LEDs to a pop bumper driver board
- How the System 80 pop bumper driver board works
- Bench check of a pop bumper driver board
- Pop bumper board wiring is in each game manual
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part One, Clay Harrell (pinrepair.com)