Macintosh Classic Capacitor Replacement Guide
Replacing electrolytic capacitors (recapping) in your Macintosh Classic is essential for restoring power stability, ensuring clean video output, and preventing long-term damage due to capacitor leakage. This guide outlines the recommended procedure and provides complete analog and logic board capacitor specifications.
Capacitor Inspection
[edit | edit source]Before recapping, visually inspect all capacitors for common signs of failure:
- Bulging Tops – Swollen or domed caps indicate internal gas buildup.
- Electrolyte Leakage – Brown/white crust or residue near leads shows capacitor failure.
- Corroded Pads or Traces – PCB staining or corrosion suggests leakage damage.
If any of these symptoms are present, immediate replacement is advised.
Macintosh Classic Capacitor List
[edit | edit source]Analog Board Capacitors
[edit | edit source]The Macintosh Classic analog board has several capacitors that may require replacement. Due to variations in board revisions, consult the specific schematic for your model. Common capacitor values include:
| Label | Capacitance | Voltage | Quantity |
|---|---|---|---|
| CF3 | 1000µF | 16V | 1x |
| CF4 | 470µF | 25V | 1x |
| CL1 | 1000µF | 25V | 1x |
| CL2 | 4.7µF | 250V | 1x |
| CL3 | 1µF | 50V | 1x |
| CP1 | 220µF | 250V | 1x |
| CP10 | 470µF | 25V | 1x |
| CP11 | 220µF | 50V | 1x |
| CP12 | 1000µF | 16V | 1x |
| CP13 | 220µF | 250V | 1x |
| CP2 | 470µF | 50V | 1x |
| CP34 | 1µF | 50V | 1x |
| CP36 | 2200µF | 10V | 1x |
| CP4 | 47µF | 25V | 1x |
| CP5 | 1µF | 50V | 1x |
| CP6 | 2200µF | 10V | 1x |
| CP7 | 1000µF | 10V | 1x |
| CP8 | 2200µF | 16V | 1x |
| CP9 | 470µF | 25V | 1x |
| CV2 | 470µF | 10V | 1x |
| CP3 | 10µF | 25V | 1x |
| CP37 | 1µF | 50V | 1x |
| CL11 | 47µF | 16V | 1x |
| CF2 | 220µF | 16V | 1x |
| CF1 | 47µF | 25V | 1x |
- Note: Capacitor labels and values may vary between board revisions. Always verify with your specific board.*
Logic Board Capacitors
[edit | edit source]The Macintosh Classic logic board contains surface-mount electrolytic capacitors prone to leakage and corrosion.
| Label | Capacitance | Voltage | Quantity |
|---|---|---|---|
| C1 – C7 | 47µF | 16V | 7x |
| C8 | 1µF | 50V | 1x |
Note: When replacing with tantalum capacitors, consider using 25V rated caps for the 47µF positions to ensure longevity.
Capacitor Replacement Procedure
[edit | edit source]- Discharge the CRT – Follow standard CRT discharge procedures before working inside.
- Remove the Logic & Analog Boards – Label cables and safely extract both boards.
- Desolder Old Capacitors – Use a quality soldering iron, braid, or pump to remove components cleanly.
- Clean the Board – Thoroughly clean any electrolyte residue with isopropyl alcohol.
- Install New Capacitors – Insert with correct polarity (check for stripe on negative side).
- Solder Carefully – Ensure clean, shiny joints without cold solder bridges.
- Trim Leads & Inspect Work – Cut excess and examine under light or magnification.
- Test for Shorts – Use a multimeter to confirm there are no shorts across power rails.
Recommended Tools
[edit | edit source]- Temperature-controlled soldering iron (fine tip)
- Desoldering braid or vacuum pump
- Quality leaded solder (0.5 mm recommended)
- Isopropyl alcohol and ESD brush
- Multimeter
- Safety goggles and insulated gloves
Voltage Adjustment After Recap
[edit | edit source]Measure voltages at the floppy drive or logic board power connector:
- +5V rail: 4.90V – 5.15V
- +12V rail: 11.9V – 12.7V
Use the analog board's trimmer potentiometer (R56) to fine-tune if necessary.
Tips for Best Results
[edit | edit source]- Always recap the logic board first – leaking caps often cause corrosion damage.
- Use quality capacitors (e.g., Nichicon, Panasonic, Rubycon).
- Turn on the system periodically to prolong capacitor lifespan.
- Replace in full sets for even aging and reliability.
- Clean the board thoroughly with isopropyl alcohol after removal.