What a good MPU does straight after the last flash

After the self-test the MPU sets up both PIAs, clears U7, reads the 32 DIP switches, lights Game Over, Ball in Play and (with credits) the credit lamp, resets drop targets, fires saucer and other ball-holding kickers, and energises the coin lockout coil unless credits are at maximum. If none of this happens after seven flashes, the board did not reach attract mode.

Systems

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

Related tips

• Reading the MPU flash code
• What each MPU LED flash proves
• No seventh MPU flash with a good solenoid fuse
• MPU LED locked on with no flicker: likely causes
• MPU stops before the seventh flash: check the 43 V at R113
• Good MPU stays LED-on with a PC power supply
• MPU boots only when U9 pins 39 and 40 are shorted
• MPU reboots right after the seventh flash

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