Partial Maze With Large Horizontal Dead Spaces

Repair Case Summary

This page documents a firsthand Partial Maze With Large Horizontal Dead Spaces repair case. It is intended for technicians and collectors troubleshooting original Pac-Man or Ms. Pac-Man arcade PCB hardware.

• Date: 2019-08-19
• Board: Original Pac-Man PCB; same board as preceding reset-circuit repair
• Category: Graphics / video RAM
• Symptoms:
  • Maze displayed only partially.
  • Large horizontal dead spaces appeared in the maze.
  • Removing previously socketed 3D while the board was running made the maze display perfectly, but all characters disappeared.
• Diagnostic observations / tests:
  • 3A and 3B were receiving bad signals.
  • Tracing narrowed the issue to the 2A-2D series.
  • Piggybacking 2A with a known-good D2115 returned the screen to normal.
• Components / locations investigated: 3D, 3A, 3B, 2A-2D, 2A, D2115
• Root cause: Bad D2115 at 2A.
• Repair: Replaced the D2115 at 2A.
• Result: The screen returned to normal.
• Repair note: This is the second repair on the PCB whose reset failure was corrected by replacing 7L.
• Search terms: Pac-Man partial maze; horizontal dead spaces; maze missing; 2A; D2115; 3A; 3B; 3D; video RAM; graphics
• Evidence: Physically verified repair / firsthand repair log

Related Repair on the Same PCB

This was the same PCB whose reset failure was first corrected by replacing the 74LS02 at 7L. See Pac-Man reset failure — 74LS02 at 7L.

Related Pac-Man / Ms. Pac-Man Repair Cases

• Static Garbage, Dead Address/Data Lines and Failed Reset
• Sparkles or Stars Around Pac-Man and Ghosts
• Notches Missing From Pac-Man and Ghost Graphics
• Pinky Jitters During Vertical Movement

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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