One or more displays work except that "1" never appears in any position.
Displays never show the digit 1
Cause: The 1 is driven like a segment, not a digit, so this is a segment fault, typically CPU chip Z16.
Checks
- Treat it as a segment problem, not a digit problem.
Fix
- Replace Z16 (7404) on the CPU board.
Systems
Related tips
- Missing digit on one or more score displays
- Display chips on the CPU board fail after swapping displays
- Scores show only a single 0 and the credit display is blank: failed 7404 at IC31
- Damage after the black and white plugs were swapped
- Boot stops after the ninth LED flash: IRQ fault
- Blanking circuit parts: C32/C84, IC7, Q5/Q1 and IC23
- Display fault: board or display?
- Displays are scanned, not lit steadily
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part Two, Clay Harrell (pinrepair.com)