What System 7 codes often turn out to mean

Code 1 or 2: often IC32, IC12 or IC31 in the memory protect circuit rather than a 2114. Code 8: a bad IC36 (sound PIA, which the factory test skips but game code uses); or, if coils pull in at power-on, a bad IC23 (555). Code 9: check IC7 pin 13 is high. Codes 3, 4, 6 and 7 usually mean a bad ROM; replace all the old ROMs with EPROMs. Codes 8 and 9 are most often a dead 5101 at IC19.

Systems

• Williams System 7

Related tips

• EPROM types used for System 3 to 7 game code
• System 7 SW1 diagnostic codes
• Flipper ROM color codes by system
• Identifying a System 3 to 7 CPU board
• System 7 CPU board test points
• Which System 3 to 7 games use which flipper ROM system
• A System 7 CPU board can run any System 3 to 7 game
• Run a System 6/7 CPU board on +5 V only

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Two, Clay Harrell (pinrepair.com)