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Screen Full of Zeros With Irregular Black Blocks
Repair Case Summary
This page documents a firsthand Screen Full of Zeros With Irregular Black Blocks repair case.
It is intended for technicians and collectors troubleshooting original Pac-Man or Ms. Pac-Man arcade PCB hardware.
- Date: 2017-04-07
- Board: Original Pac-Man PCB
- Category: Scratchpad RAM / boot failure
- Symptoms:
- Startup screen full of 0s.
- Irregular blocks of black space appeared among the zeros.
- Diagnostic observations / tests:
- All scratchpad RAM from 4R through 4K was temporarily replaced with a known-good set and the board booted.
- The removed 2114 RAMs were tested individually.
- The failure could be reproduced with the bad RAM installed at 4K.
- Components / locations investigated: 4R-4K scratchpad RAM, 4K, 2114 RAM
- Root cause: One bad 2114 scratchpad RAM, originally at 4K.
- Repair: Replaced the bad 2114 RAM.
- Result: The board booted normally.
- Search terms: Pac-Man screen full of zeros; 0s on screen; black blocks; 2114 RAM; scratchpad RAM; 4K; 4R; 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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