None of the computer-controlled lamps light, though the general illumination works.

Every CPU-controlled lamp is out

Cause: The backbox fuse on the blue/white wires that feeds the lamp matrix (F2, beside the large 30,000 µF capacitor and bridge) has blown.

Checks

• Check the lamp matrix fuse in the backbox next to the big filter capacitor.
• If it blows again, test the bridge rectifier and the 30,000 µF capacitor for shorts before fitting another fuse.

Fix

• Replace the fuse with the correct rating once the bridge and capacitor test good.

Systems

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

Related tips

• DMD shows lines or lights up fully, and no CPU lamps work
• All controlled lamps out, GI fine: blown lamp supply fuse by the big filter cap
• Bulb spares: #44 for CPU lamps, #47 for general illumination
• One controlled lamp never lights, bulb is good
• A group of general illumination lamps is out
• General illumination dead or dim
• A single lamp is out: the usual causes
• A group of clock lamps never light with good wiring: reseat the bulbs in their sockets

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