The score displays act up and, during the display test, all the lamps flicker, even with a new power supply, a known-good lamp board and a new solenoid board fitted.

Displays misbehave and lamps flicker in display test: bad crimp on a 5 V pin

Cause: A badly crimped terminal on one of the 5 V supply pins, giving an intermittent logic supply.

Checks

• Measure 5 V at the MPU while wiggling each power connector.
• Inspect every 5 V and ground pin in the power connectors for a loose or poorly crimped terminal, even after repinning.
• Try one display at a time to rule out a single faulty display.

Fix

• Recrimp or replace the bad 5 V terminal.

Systems

• Bally MPU AS-2518-17

Games

• Evel Knievel

Related tips

• Credit digits stay blank in play but work in display test: DIP switch 20
• Solenoid driver board J3 pin functions
• Buy crimp pins loose and tin plated
• Burnt pins at solenoid driver J3
• Three flashes and 8s or 9s in the hundreds digit

Source: Pinball Repair help group!! (Facebook group)