At switch-on the display shows a random message, flashes and repeats, sometimes with beeps; the CPU LED blinks rapidly then pauses each time; the test button does nothing.

Nonsense message at boot, game stuck in a loop

Cause: Most often battery corrosion on the DS1210 at U6 or a failed U11 74HC123AN; also dirty ribbon cable contacts or a bad CPU-to-driver ribbon cable.

Checks

• Inspect U6 and the battery area for corrosion.
• Reseat every backbox ribbon cable.
• Swap the CPU-to-driver ribbon cable.

Fix

• Repair corrosion and replace U6 if damaged.
• Replace U11 with a 74HC123AN.
• Update the game EPROM to the latest version.

Systems

• Gottlieb System 3

Games

• Cue Ball Wizard

Related tips

• Reading the CPU board LED
• CPU board will not boot, or keeps rebooting
• Reset capacitor workaround for boot garbage
• Game resets every two seconds
• Lithium battery leak damaging the CPU board
• CPU board LED never lights
• Garbage on the dot matrix at power-on
• Booting a CPU board on the bench

Source: Repairing Gottlieb System 3 Electronic Pinball Games from 1989 to 1996, Clay Harrell (pinrepair.com)