The GI lamps flash in attract mode but do not come on during a game.

Mr. & Mrs. Pac-Man GI flashes in attract but stays off in play

Cause: The GI is switched by a triac on the cabinet power supply board, driven from a small under-playfield flasher board where a lamp SCR feeds a MOC3011 with a dummy #555 bulb as load. Usually that bulb is burned out; also cracked joints on the flasher board, triac wiring, or the MOC3011.

Checks

• Check the #555 bulb on the flasher board.
• Inspect the flasher board joints and the triac connections.

Fix

• Replace the bulb, reflow joints, or replace the MOC3011.

Systems

• Bally MPU AS-2518-35

Games

• Mr. & Mrs. Pac-Man

Related tips

• One drop target lamp won't light after board work: broken wire in the harness
• Controlled lamps stuck or not flashing: reflow MPU and lamp driver header pins
• Two inserts faintly lit all the time: failed lamp driver SCR
• AS-2518-14 vs AS-2518-23 lamp driver boards
• Test lamp SCRs with the power off
• Substitute SCRs for the lamp driver board
• Lamp driver, auxiliary lamp driver and display driver test points
• How Bally controlled lamps are powered and switched

Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Three, Clay Harrell (pinrepair.com)