A World Cup with a replacement or rebuilt CPU board does not start.

World Cup will not boot after a CPU board swap

Cause: World Cup needs its own flipper ROM 2 at IC17, different from every color group of flipper ROMs.

Checks

• Check which flipper ROM is fitted at IC17.

Fix

• Install the World Cup-specific flipper ROM 2 at IC17.

Systems

• Williams System 3

Games

• World Cup

Related tips

• World Cup will not boot on standard white flipper ROMs
• CPU never starts: check the reset line at IC1 pin 40
• Intermittent lockups with both CPU LEDs on
• System 3 CPU board reset circuit modification
• "Adjust Failure" at power-on
• Random lockups from the 12 V logic pin
• Usual causes of lock-ups and resets
• Reset or lock-up: which points where

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