M-200 with all 32 DIP switches off runs a built-in self test

If every DIP switch is off at power-on, the M-200 flashes its LED seven times and goes into a test that pulses each solenoid in turn, flashes the controlled lamps and steps each display digit.

Systems

• Stern MPU-200

Related tips

• All DIP switches off can start a self-test after boot
• A Stern M-200 set for 2732s runs any Bally or Stern game 1977-1985
• Test EPROM: the least an MPU needs to run it
• Stern games from 1980 on need an M-200 MPU
• U9 pin 2 (halt) is not high
• Seven flashes but no attract mode
• M-200 flashes seven times but the game misbehaves or repeats one number in audits
• M-200 clock-speed jumpers E32-E33 and E34-E35

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