The image on the small display is scrambled, while the game itself runs.

Small 128 x 16 display looks garbled

Cause: R95, a 33k 1/2 W resistor on the display board, has drifted high or gone open. The glass is usually fine.

Checks

• Measure R95.

Fix

• Replace R95 with a 33k 1/2 W resistor.

Systems

• Data East CPU Version 3

Games

• Batman
• Checkpoint
• Hook
• Star Trek
• Teenage Mutant Ninja Turtles

Related tips

• Small 128 x 16 display connector J2 pinout
• Small display much too bright (wrong D10 on a -00 supply)
• Test a loose 128 x 16 display glass
• Small display shows vertical lines
• DMD shows lines or garbage and no controlled lamps light
• Which DMD brands are hit by a blown lamp fuse
• Dot matrix shows lines or lights solid, and no CPU lamps work
• 128 x 32 display dead: check the PALs at U2 and U16

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