Random horizontal lines or garbage on the dot matrix (on 128x16 displays the whole display may then light solid). The game still starts and plays balls, but no CPU-controlled lamps light.

DMD shows lines or garbage and no controlled lamps light

Cause: The 8 A slow-blow 18 V lamp matrix fuse in the backbox (blue/white wire at its holder) has blown. These displays take their 12 V from that bridge and capacitor through CN5 on the power supply, not from the supply's own 12 V on CN6.

Checks

• Test the backbox 18 V lamp matrix fuse out of its holder.
• If it blows again at once, check the lamp matrix bridge and look for a short in the lamp wiring.

Fix

• Replace the fuse with the correct 8 A slow-blow.
• Repair the bridge, capacitor or lamp short if the fuse keeps failing.

Systems

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

Games

• Adventures of Rocky and Bullwinkle and Friends
• Batman
• Checkpoint
• Guns N' Roses
• Hook
• Jurassic Park
• Last Action Hero
• Lethal Weapon 3
• Star Trek
• Star Wars
• Tales from the Crypt
• Teenage Mutant Ninja Turtles
• The Who's Tommy Pinball Wizard
• WWF Royal Rumble

Related tips

• Dot matrix shows lines or lights solid, and no CPU lamps work
• DMD dark after work in the backbox: transformer wire pulled out of its plug
• Score display boards by game range
• After a bulb change, coils dead and a flasher fires the knocker: blown supply fuse
• Small display shows vertical lines
• DMD shows random garbage after reassembly: failed display driver board
• A 520-5047-02 supply can stand in for a 520-5047-01
• Adding jumper wires across DB1 and C4 (520-5047-00/-01/-02)

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