Macintosh Classic II Capacitor Replacement Guide

Replacing electrolytic capacitors (recapping) in your Macintosh Classic II is essential for restoring power stability, ensuring clean video output, and preventing long‑term damage due to leakage. This guide outlines the recommended procedure and provides complete analog and logic board capacitor specifications.

🔍 Capacitor Inspection

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 failure.
Corroded Pads or Traces – PCB staining or corrosion suggests damage.

If any symptoms are present, immediate replacement is advised.

📋 Macintosh Classic II Capacitor List

🧯 Analog Board Capacitors

The Classic II shares its analog board with the Classic. Due to board revisions, labels may vary—always verify against your schematic.

**Macintosh Classic I + II Analog Board Capacitor Specifications**
Label	Capacitance	Voltage	Qty
CF3	1000 µF	16 V	1
CF4	470 µF	25 V	1
CL1	1000 µF	25 V	1
CL2	4.7 µF	250 V	1
CL3	1 µF	50 V	1
CP1	220 µF	250 V	1
CP10	470 µF	25 V	1
CP11	220 µF	50 V	1
CP12	1000 µF	16 V	1
CP13	220 µF	250 V	1
CP2	470 µF	50 V	1
CP34	1 µF	50 V	1
CP36	2200 µF	10 V	1
CP4	47 µF	25 V	1
CP5	1 µF	50 V	1
CP6	2200 µF	10 V	1
CP7	1000 µF	10 V	1
CP8	2200 µF	16 V	1
CP9	470 µF	25 V	1
CV2	470 µF	10 V	1
CP3	10 µF	25 V	1
CP37	1 µF	50 V	1
CL11	47 µF	16 V	1
CF2	220 µF	16 V	1
CF1	47 µF	25 V	1

Note: Values may vary between revisions—always cross-check your board.*

🔧 Logic Board Capacitors

Two logic board revisions exist—Rev A has 13 caps, Rev B has 17.

**Logic Board Capacitor Specifications**
Revision	Value	Voltage	Qty
Rev A	47 µF	16 V	3
	10 µF	16 V	8
	1 µF	50 V	2
Rev B	47 µF	16 V	3
	10 µF	16 V	12
	1 µF	50 V	2

Tip: If substituting tantalum, choose 25 V ratings for the 47 µF positions.*

Macintosh Classic II (Rev A) Logic Board Recap Diagram
Macintosh Classic II (Rev B) Logic Board Recap Diagram

🛠️ Capacitor Replacement Procedure

Discharge the CRT – Follow standard CRT discharge steps before opening the case.
Remove the Boards – Label connectors; carefully extract the logic and analog boards.
Desolder Old Caps – Use a temperature‑controlled iron with braid or pump for clean removal.
Clean the PCB – Remove all electrolyte residue with 99 % IPA and an ESD‑safe brush.
Install New Caps – Observe polarity (negative stripe); seat flush to the board.
Solder Carefully – Aim for shiny, sloped joints; avoid cold bridges.
Trim Leads & Inspect – Cut excess lead length and check with magnification.
Test for Shorts – Verify with a multimeter across each power rail.

🧰 Recommended Tools

Temperature‑controlled soldering iron (fine tip)
Desoldering braid or vacuum pump
Leaded solder, ~0.5 mm diameter
99 % isopropyl alcohol & ESD‑safe brush
Multimeter
Safety goggles & insulated gloves

⚙️ Voltage Adjustment After Recap

With boards reinstalled, measure at the floppy‑drive power pins:

+5 V rail: 4.90 – 5.15 V
+12 V rail: 11.9 – 12.7 V

Use the analog board’s variable resistor (PP1) to fine‑tune.

💡 Tips for Best Results

Recap the logic board first—its leakage often damages the analog side.
Use top‑tier caps (Nichicon, Panasonic, Rubycon).
Power on the machine periodically after recap to “exercise” new caps.
Replace complete sets for uniform aging and reliability.
Always clean the board thoroughly post‑recap.

🔗 Related Pages