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Screen Full of Red 2s Caused by Loose Sync Bus Controller
Repair Case Summary
This page documents a firsthand Screen Full of Red 2s Caused by Loose Sync Bus Controller repair case.
It is intended for technicians and collectors troubleshooting original Pac-Man or Ms. Pac-Man arcade PCB hardware.
- Date: 2017-04-08
- Board: Original Pac-Man PCB
- Category: Boot failure / daughter card connection
- Symptoms:
- Entire screen filled with red 2s at startup.
- Pressing on the Z80 made no change.
- Pressing down on the Z80 Sync Bus Controller caused the board to boot normally.
- Diagnostic observations / tests:
- The Sync Bus Controller card had been bumped and was not strapped down.
- Components / locations investigated: Z80 Sync Bus Controller card
- Root cause: Poor connection at the Sync Bus Controller card.
- Repair: Pressed the Sync Bus Controller firmly into place and secured it with a zip tie.
- Result: No further problems were observed.
- Search terms: Pac-Man red 2s; screen full of 2s; Sync Bus Controller; Z80 daughter card; loose card; boot failure
- Evidence: Physically verified repair / firsthand repair log
How to Use This Repair Record
This is a firsthand physical repair case. The same symptom on another Pac-Man or Ms. Pac-Man PCB can have a different electrical cause. Use the documented diagnostic observations and tests to guide troubleshooting rather than replacing a component solely because it repaired this board.
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