Digits appear three or four at a time in a slow sweep across the displays, never all lit together, though scoring is correct.

Alphanumeric displays show only a few digits at a time

Cause: Weak high voltage, as low as 50 V, from failing R8/R9 (39k), the 100 µF 150 V capacitors C10/C11, or the 0.1 µF 500 V capacitors C12/C13.

Checks

• Measure the ±100 V outputs.

Fix

• Replace the faulty resistors or capacitors.

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 displays dim or dead
• Run alphanumeric displays at 91 V for longer life
• Check the ±100 V display supply at CN5
• Displays weak with low 100 V even unplugged
• High-voltage display fuse F3 keeps blowing
• Alphanumeric supply: parts for the +100 V side
• Alphanumeric supply: parts for the -100 V side
• Small display shows vertical lines

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