iMac Logic Board 820-3299-A: Symptoms and Repair Options

iMac logic board repair

Overview

The logic board 820-3299-A in certain iMac models is known for power and GPU-related issues. We diagnose at component level and repair defective circuits where possible.

Typical Symptoms

  • No power, chime, or video output
  • Boot freezes or random shutdowns
  • Artifacts/stripes caused by GPU defects
  • USB and I/O instability
  • Short circuits on power rails

Repair Options

  • Component-level repair of power, SMC and GPU circuits
  • Reballing/replacement of defective chips where feasible
  • Board swap only as last resort