Checklist for a dead small or medium dot matrix display

Steps

• Measure -110, -98, +68, +12 and +5 V at the display board (within 10 percent).
• Check the +5 V connection to the display board again.
• Check the backbox 18 V lamp matrix fuse.
• Check the data ribbon cable from the CPU board to the display.
• On a 128 x 16 display, check or replace R95.
• Replace the display ROMs.

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 3
• Data East/Sega CPU Version 3b

Related tips

• Voltages a small or medium dot matrix display needs
• The dot matrix display has its own computer
• Dot matrix controller CPUs by display size
• Small display shows vertical lines
• The three Data East dot matrix display sizes
• Display not working: check +5 V at the controller first
• Dot matrix controller boards
• Dot matrix display goes blank after a few minutes

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