The +5 V output is missing.

Power supply gives no +5 V

Cause: The +5 V regulator IC1 (MC1723) or pass transistor TR5 (2N6057) has failed, or a capacitor around them has.

Checks

• Before changing IC1 or TR5, check C2 (100 uF 25 V), C3 (47 uF 25 V), C5 (470 pF 50 V), C6 (0.1 uF 50 V) and C7 (330 uF 25 V).

Fix

• Replace the failed capacitor(s), then IC1 and TR5 if still dead.

Systems

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

Related tips

• No or low +5 V from the power supply
• Power supply board versions are not interchangeable
• Z1 on the power supply is a varistor, not a diac
• Power supply board versions and their +5 V filter capacitors
• Power supply CN1 pinout, pins 1-6
• Power supply CN1 pinout, pins 7-12
• Low +12 V (below 10.5 V)
• A 520-5047-02 supply can stand in for a 520-5047-01

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