Flippers work for about five minutes and then quit; a different MPU cures it.

Flippers stop working after a few minutes of play

Cause: MPU J4, which carries the flipper relay enable to the solenoid driver board, has corroded or cracked pins, or SDB J1 pins or traces are bad, or a PIA is failing.

Checks

• Inspect MPU J4 header pins and SDB J1 pins and traces.

Fix

• Repair the connectors; in the reported case swapping U10 and U11 fixed it, so replace the failing PIA.

Systems

• Bally MPU AS-2518-35

Games

• Rolling Stones

Related tips

• Flippers weak or intermittent from the solenoid driver board
• Flipper weak, dead, or machine-gunning
• Flippers dead though fuses and EOS switches are good
• Game reboots at random: R11 heating Q5
• Game resets or locks up when the flippers are used
• MPU locks if switched off and quickly back on
• MPU stops before the 7th LED flash (no 43 V)
• MPU stops before the seventh flash: check the 43 V at R113

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