A game starts, the ball is served and the game freezes.

Game serves a ball then freezes

Cause: The game PROM is missing or poorly seated; also resistors R122-R131.

Checks

• Reseat or fit the Z23 PROM.
• Check R122-R131.

Fix

• Replace the PROM or the faulty resistor.

Systems

• Gottlieb System 1

Related tips

• Spare chips for System 1 boards
• The six Rockwell "spider" chips on the CPU board
• Which spider chips fail and why
• Swapped U4 or U5 spider still does not work
• Check the TC3 jumper plug on the CPU board
• Odd high scores usually mean a bad 5101 RAM
• Aftermarket System 1 CPU boards
• Dead CPU board: first checks

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