At power-on parts of the display, starting with the corners and edges, are blank; they fill in after a few minutes as it warms.
Display dark at the edges until it warms up (outgassed glass)
Cause: The display glass is outgassing: impurities from the worn electrodes spoil the gas inside. There is no repair.
Checks
- Watch the display from a cold start.
Fix
- Replace the display glass as soon as this starts. A failing glass loads the high-voltage supply heavily and can burn the power supply.
The display power supply carries about 100 V or more; work on it with the game unplugged and let the capacitors discharge.
Systems
Related tips
- Display freezes or shows garbage after warming up: reseat the display controller ROMs
- 128 x 32 display dead: check the PALs at U2 and U16
- Large display still unstable after the harness fix
- Test a loose 128 x 16 display glass
- Large 192 x 64 display power connectors by display maker
- 192 x 64 display blanks out or the game resets
- Build your own 192 x 64 display power harness
- Display not working: check +5 V at the controller first
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)