Macintosh LC III+ Capacitor Replacement Guide
Replacing the electrolytic capacitors (recapping) in the Macintosh LC III+ is essential for long-term reliability.
Known Factory Defect: C22
[edit | edit source]Important: Like the LC III, the Macintosh LC III+ has a known manufacturing defect where capacitor C22 was installed with reversed polarity at the factory. The silkscreen marking on the PCB is printed backwards.
When replacing capacitors, install C22 with correct polarity according to the capacitor's markings, not the PCB silkscreen.
Symptoms of Capacitor Failure
[edit | edit source]- No audio — Most common early symptom
- Distorted or crackling audio
- Boot failures or instability
- Visible electrolyte leakage — Brown or black residue around capacitors
- Corrosion on PCB traces
Capacitor List
[edit | edit source]Logic Board Capacitors
[edit | edit source]The LC III+ uses the same capacitor layout as the LC III.
| Designator | Capacitance | Voltage | Notes |
|---|---|---|---|
| C1 | 1 µF | 50V | |
| C2 | 1 µF | 50V | |
| C3 | 10 µF | 16V | |
| C4 | 10 µF | 16V | |
| C5 | 10 µF | 16V | |
| C6 | 10 µF | 16V | |
| C7 | 47 µF | 16V | |
| C8 | 47 µF | 16V | |
| C9 | 47 µF | 16V | |
| C10 | 47 µF | 16V | |
| C11 | 47 µF | 16V | |
| C12 | 47 µF | 16V | |
| C13 | 47 µF | 16V | |
| C14 | 47 µF | 16V | |
| C15 | 100 µF | 6.3V | |
| C16 | 100 µF | 6.3V | |
| C17 | 100 µF | 6.3V | |
| C22 | 47 µF | 16V | Factory reversed polarity — install correctly! |
Power Supply Capacitors
[edit | edit source]Refer to the Macintosh LC Power Supply Recap Guide for PSU-specific information.
Capacitor Replacement Procedure
[edit | edit source]Tools Required
[edit | edit source]- Temperature-controlled soldering iron (recommended: 300-350°C)
- Fine tip for SMD work
- Desoldering braid or solder wick
- Flux (no-clean recommended)
- Isopropyl alcohol (99%)
- Soft brush (ESD-safe)
- Multimeter
- Replacement SMD electrolytic capacitors
Procedure
[edit | edit source]- Remove the logic board — Disconnect all cables, remove screws, and carefully lift the board.
- Document capacitor positions — Note polarity markings before removal.
- Clean the area — Remove any leaked electrolyte with isopropyl alcohol.
- Remove old capacitors — Heat one pad while gently lifting the capacitor. Alternate between pads.
- Clean the pads — Remove old solder with desoldering braid. Clean with IPA.
- Inspect for damage — Check traces and vias for corrosion.
- Install new capacitors — Observe polarity. For C22: ignore the PCB silkscreen.
- Clean residue — Remove flux with isopropyl alcohol.
- Test continuity — Verify no shorts between +5V, +12V, and ground.
- Reassemble and test
Important Notes
[edit | edit source]- C22 silkscreen error — The PCB marking is wrong. Install based on the capacitor's polarity marking.
- Polarity matters — SMD electrolytics will fail if installed backwards.
- Use equivalent or better specs — Match capacitance; voltage rating can be equal or higher.
Related Pages
[edit | edit source]External Resources
[edit | edit source]- Recap-a-Mac: Macintosh LC III Capacitor Guide (same board as LC III)