The 1/4 A 250 V slow-blow fuse F3, protecting the ±100 V display supply, blows.

High-voltage display fuse F3 keeps blowing

Cause: A failed high-voltage section on the supply, or a shorted display glass or UDN7180 driver chip on the display controller.

Checks

• Unplug CN5, fit a new fuse and power up.
• If it blows with CN5 off, the supply needs its high-voltage section rebuilt.
• If it blows only with CN5 connected, suspect a shorted glass or UDN7180.

Fix

• Rebuild the supply's high-voltage section, or replace the faulty glass or chip.

The display power supply carries about 100 V or more; work on it with the game unplugged and let the capacitors discharge.

Systems

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

Related tips

• Alphanumeric segments still missing: the UDN chips
• Check the ±100 V display supply at CN5
• Alphanumeric displays dim or dead
• Alphanumeric supply: parts for the +100 V side
• Alphanumeric supply: parts for the -100 V side
• Rebuild the alphanumeric ±100 V section
• Alphanumeric displays show only a few digits at a time
• Combining two 27020 display images into one 27040

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