Missing and Out-of-Tempo Sounds From Broken Trace at 1M

Repair Case Summary

This page documents a firsthand Missing and Out-of-Tempo Sounds From Broken Trace at 1M 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: Sound
• Symptoms:
  • Sound was incorrect, especially during intermission scenes.
  • In test mode there was no sound when the joystick was pressed down.
  • Parts of the intermission music played out of tempo.
• Diagnostic observations / tests:
  • Logic-probe troubleshooting narrowed the issue to the CD4066 at 1M.
  • The 4066 had been replaced previously without a socket and appeared to be a used part.
  • Continuity testing found a broken trace between 1M pin 3 and resistor R2.
• Components / locations investigated: 1M, CD4066, 1M pin 3, R2
• Root cause: Broken trace from 1M pin 3 to R2; questionable prior 4066 installation.
• Repair: Repaired the trace under 1M, installed a socket, and installed a good 4066.
• Result: All sounds were restored.
• Search terms: Pac-Man sound wrong; intermission music out of tempo; missing test sound; 1M; CD4066; R2; broken trace; sound circuit
• Evidence: Physically verified repair / firsthand repair log

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

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• No Sound: Signal Trace Leads to 74LS139 at 7M

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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