The left-most character of the credit display shows garbage.

F-14 Tomcat: left credit-display character scrambled

Cause: Not the display board: a shorted PIA and 74154 chip on the CPU board.

Fix

• Replace the shorted PIA and the 74154 on the CPU board.

Systems

• Williams System 11A

Games

• F-14 Tomcat

Related tips

• Displays out, flippers and ball eject dead after display glitches
• System 11 switch matrix: connectors and chips
• Switch matrix dead after an under-playfield adjustment with power on
• Fixing a dead switch column on the CPU board
• Fixing a dead switch row on the CPU board
• F-14 Tomcat pop bumper locks on once a game starts
• Displays show only every other digit ("0_0_0")
• Odd DMD screens or "command 9c" errors with matching ROMs

Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell