The thousands digit on players 1 and 3 glows faintly, and lights along with the credit display when a game starts.
Genie: 1000s digit glows on players 1 and 3
Cause: A failed 7408 at Z21 on the CPU board.
Fix
- Replace Z21 (7408).
Systems
Games
Related tips
- Genie: game PROM letter
- Damage after the black and white plugs were swapped
- Background sound never stops at game over: sound-line driver chip
- Kicker coil locks on again after a new TIP122: dead 7408 gate on the driver board
- Outhole kicker locks on whenever the service menu is entered: bad 7408 at U20
- How a coil or flasher is switched: PIA to TTL to pre-driver to driver
- A coil or flasher comes on and stays on at power-up
- Which logic chips drive which solenoid transistor pairs
Source: Gottlieb System 1 Pinball Repair from 1977 to 1980, Clay Harrell (pinrepair.com)