All DIP switches off can start a self-test after boot

On some boards, with every MPU DIP switch off, the game goes straight into a self-test after the seventh flash, pulsing each coil, flashing lamps and stepping digits on the displays. Set the DIP switches before assuming a fault.

Systems

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

Related tips

• M-200 with all 32 DIP switches off runs a built-in self test
• Get the MPU booting before you change any ROM jumpers
• Game will not boot, or MPU damaged, after swapping -35 and -133 boards
• Seven flashes but no attract mode
• Intermittent MPU faults from old closed-frame chip sockets
• Game locks up entering bookkeeping after a battery change
• Everything runs slow (half-speed tune, late scoring)
• Stern M-200 occasionally will not boot and the MPU reset button does nothing

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