Digits look wrong on several displays, or the number 1 shows incorrectly.

Wrong-looking digits or bad "1"s

Cause: Strange digits: a 7448 at Z16 (players 1-2 and credit) or Z17 (players 3-4). Bad 1s: Z13, Z14 or Z15.

Fix

• Replace the suspect chip.

Systems

• Gottlieb System 1

Related tips

• Never plug displays with the power on
• Displays are scanned, not lit steadily
• Power supply bring-up, step 3: displays
• Genie: 1000s digit glows on players 1 and 3
• Displays light at once showing zeros
• Displays show gibberish
• Only one credit, blank bookkeeping or replays will not set
• Dead CPU board: first checks

Source: Gottlieb System 1 Pinball Repair from 1977 to 1980, Clay Harrell (pinrepair.com)