Score displays pulse with the backglass lighting effects; unplugging the auxiliary lamp driver board stops it. Haunted House's displays near that board are the worst.
Displays flicker in time with the backglass light show
Cause: Weak ground to the auxiliary lamp driver board, or cold joints on it.
Fix
- Add the extra ground wire from the auxiliary lamp driver board to the power supply frame.
- Reflow any cold or open joints on the back of the board.
Systems
Games
Related tips
- Displays flicker on games with an auxiliary lamp board
- Backbox chase lights run from their own board
- Backbox chase lights not running
- Basement (lower playfield) score display dark: wire pushed out of the A10-J6 plug
- Haunted House driver board: which transistor runs which coil
- Driving the Haunted House up-kicker from a pop bumper driver board
- Coils pulse briefly at switch-on on Volcano, Black Hole and Haunted House
- Telling a bad display driver from a bad display tube
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part One, Clay Harrell (pinrepair.com)