A pop bumper coil energizes and stays on when a game is started.
Pop bumper locks on as soon as a game starts
Cause: The PBDB has +5 V but has lost its logic (DC) ground on pin 6, which comes from CPU A1-J6 pin 9 under the battery; or a cracked header joint, most often pin 1 to Q1's case; or a shorted Q1.
Checks
- Check the ground at PBDB pin 6 against the cabinet ground strap.
- Inspect CPU J6 pin 9 and its board finger for corrosion.
- Look for cracked solder around the PBDB header pins, especially pin 1.
- Diode-test Q1 (2N6057/2N6059): black lead on a case screw, red on each leg, expect 0.4 to 0.6.
Fix
- Repin CPU J6 or clean the finger.
- Reflow the PBDB header pins.
- Replace Q1 (a TIP102 can be used).
Systems
Related tips
- A pop bumper never fires
- How the pop bumper driver board fires its coil
- Under-playfield pop bumper driver boards protect the coils
- Pop bumper fires erratically or several times
- 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
- Has the pop bumper board factory fix been done?
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part One, Clay Harrell (pinrepair.com)