Random resets or a game that will not boot.

Resets from power supply connectors CN1 and CN2

Cause: Cracked or cold solder joints, or burnt pins, on the square connectors CN1 (all incoming transformer power) or CN2 (central ground). Pins 10-12 of CN1, carrying the 9 V AC for the +5 V and the sound board +/-12 V, burn most often.

Checks

• Look for scorching on the CN1 housing and pins, both on the board and in the plug.

Fix

• Reflow the header joints, or replace both halves of a burnt connector with new pins.

Switch off and unplug before working on the power supply; the transformer feeds are live.

Systems

• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b

Related tips

• Square power supply plug part numbers
• Power supply CN4 has no key: refit it carefully
• Burnt GI pin on the Data East power supply header: move it to a spare pin
• Burnt 12-pin power supply input plug stops the game booting
• Game shows ROM versions and speaks, then nothing (burnt 3J1)
• Random resets from the power supply DB1 bridge
• Power supply CN1 pinout, pins 7-12
• Power supply board versions are not interchangeable

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Two, Clay Harrell (pinrepair.com)