Every display works but flashes quickly.

All displays strobe or flash rapidly

Cause: When all displays do it, look at the MPU: U9, U10, U11 and U20 and their traces (especially after battery corrosion), the 555 timer, or resistors R26 and R27. Cracked headers usually affect single displays.

Checks

• Inspect and test those MPU parts and traces.

Fix

• Repair traces or replace the failed chips or resistors.

Systems

• Bally MPU AS-2518-17
• Bally MPU AS-2518-35
• Stern MPU-100
• Stern MPU-200

Related tips

• Displays strobe wildly in one game only
• All score displays blank with the MPU fully booting
• Flickering score displays
• Score display J1 to MPU J1 connections
• All digits on all displays show 2s or 7s
• First checks before repairing Bally score displays
• Only even-numbered score displays show numbers
• Same digit missing or stuck on every display

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