Reading the CPU board LED

A booted CPU board flashes its LED steadily. A burst of very fast flashing, a short pause and a repeat usually points to a weak memory battery or a bad U11.

Systems

• Gottlieb System 3

Related tips

• CPU board will not boot, or keeps rebooting
• Nonsense message at boot, game stuck in a loop
• Reset capacitor workaround for boot garbage
• Game resets every two seconds
• Checking and setting +5 V at the CPU board
• CPU board LED never lights
• CPU board 26285 versus 26285-1
• Main chips on the CPU board

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