The score displays strobe or flicker, and the display high voltage measures low even with a different known-good solenoid driver/high voltage board fitted.
Displays strobe on early Bally SS: check the J3 ground pin for the HV circuit
Cause: A failed female crimp pin at J3 pin 3 on the solenoid driver board connector, which carries the ground for C26 in the high voltage section.
Checks
- Measure the regulated and unregulated display voltages at the board's test points with the board in the game.
- If a second known-good board shows the same low voltage, suspect the harness rather than the board.
- Inspect and test the pin at J3-3.
Fix
- Repin J3 (at least pin 3) with new crimp pins and re-measure the high voltage.
The display supply on this board runs at well over 100 V DC. Work with the game off and take care when measuring with power on.
Systems
Related tips
- Where the display high voltage enters and leaves the solenoid driver board
- Rebuilding the solenoid driver board high-voltage section
- High-voltage section parts on the solenoid driver board
- Rebuild the solenoid driver board high-voltage section
- Bally 7-digit display misbehaves wherever it is fitted: replace the decoder chip
- One score display dark: poor contact at MPU J1 pin 20
- Score displays flicker and seem to scroll: weak high voltage, power board replaced
- Flickering score displays
Source: Pinball Repair help group!! (Facebook group)