One or more score displays flicker, including playfield-mounted displays such as those on Black Hole and Haunted House.
Score displays flicker
Cause: The display return comes back to the power supply on two separate pairs of wires, so one poor pin breaks the ground for some displays; playfield displays also suffer intermittent grounds.
Fix
- Short the two pairs of display ground wires together.
- Check and repin the display connectors and the playfield display's ground.
Systems
Related tips
- Flickering displays and erratic pops from a poor J3 ground
- The display voltages to check
- System 80 schematics' 'offset' voltages are DC bias for the display filaments
- 60 V and 42 V disappear when the displays are connected
- Intermittent faults from cracked solder joints on early boards
- Coils lock on and burn because of the Gottlieb ground fault
- Which System 80 power supply boards are interchangeable
- First power-up, step 3: run the power supply on its own
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part One, Clay Harrell (pinrepair.com)