Flicker and five flashes, then the sequence stops.

Five flashes only: U12 timer or open R113

Cause: U11 PIA or its socket, the U12 555 timer that makes the display interrupt, or the zero-crossing feed. The 2k resistor R113 near J4 runs hot and often opens.

Checks

• Measure R113 for about 2k ohms.
• Check U12 and its parts.

Fix

• Replace R113, U12 (555) or U11 as found.

Systems

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

Related tips

• One flash only: U7 6810 RAM
• Two flashes only: U8 5101 RAM
• Three flashes only: U10 PIA
• Blanking stays low: timer, C31 and Q5
• Displays flash bright and speakers noisy, game does nothing
• Still no seventh flash with F4 good
• Flicker but no first flash
• The bulb next to the solenoid expander board must work

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