Bench-testing a CPU board on +5 V

Steps

• Put the CPU board on an insulating mat; it needs only +5 V and ground to boot.
• Use a regulated supply (an old computer supply works: red is +5 V, black ground) set to 4.9-5.1 V.
• Connect to the +5 V and ground test points beside the battery (easiest), or to CN17 at the upper left: pins 1-3 ground, 4-6 +5 V, 7 key, 8-9 unused.
• Switch on: the board should boot as in the game. Then use a logic probe on the matrix connectors, EPROM and CPU address and data lines.

Systems

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

Related tips

• Other CPU jumpers and what they set
• CPU boards are only downward compatible
• CPU EPROM jumpers J4 and J5
• CPU board versions 520-5003-01, -02 and -03
• Where the TIP122 drivers are on the CPU board
• CPU board PIA positions and jobs
• CPU jumpers J4 and J5 set the EPROM size at 5C
• Full CPU jumper settings by board version

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