RetroTechCollection

Apple Lisa Capacitor Replacement Guide

Replacing electrolytic and safety capacitors (recapping) in your Apple Lisa is essential for long-term reliability. The Lisa's power supply contains notorious RIFA safety capacitors that fail over time, while electrolytic capacitors throughout the system degrade and can damage circuit boards.

Safety Warning

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Capacitor Inspection

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Before beginning replacement, inspect for:

  • Cracked or Bulging Capacitors — RIFA capacitors often show visible cracking in their outer coating
  • Electrolyte Leakage — Brown or black residue around capacitor bases indicates leakage
  • Corrosion — Green or white deposits on PCB traces near capacitors
  • Burn Marks — Discoloration on PCB indicating previous capacitor failure

RIFA Safety Capacitors

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The most critical capacitors to replace in any Lisa are the RIFA-brand (or equivalent era) safety capacitors in the power supply. These capacitors are essential for EMI filtering but absorb moisture through their plastic casings over decades, leading to spectacular failures.

RIFA Failure Symptoms

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  • Loud pop or bang when powering on
  • Smoke and acrid smell
  • Tripping of household circuit breaker
  • Complete power supply failure

RIFA Replacement

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ALWAYS replace RIFA capacitors before first power-on of a long-stored Lisa.

Replace with modern X2-rated safety capacitors:

Common RIFA Replacements
Original Value Voltage Replacement Type
0.1µF (100nF) 250V AC X2 Safety Capacitor, 275V AC minimum
0.22µF (220nF) 250V AC X2 Safety Capacitor, 275V AC minimum
0.047µF (47nF) 250V AC X2 Safety Capacitor, 275V AC minimum
0.0022µF (2.2nF) 250V AC Y2 Safety Capacitor (if Y-rated position)

Power Supply Electrolytic Capacitors

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The Lisa power supply contains several electrolytic capacitors that should be replaced during a full recap:

Power Supply Electrolytic Capacitors (Typical)
Reference Capacitance Voltage Type
C1 470µF 200V Electrolytic (main filter)
C2 470µF 200V Electrolytic (main filter)
C3 1000µF 16V Electrolytic
C4 47µF 25V Electrolytic
C5 47µF 25V Electrolytic
C6 1000µF 16V Electrolytic
C7 2200µF 16V Electrolytic

Note: Values may vary by power supply revision. Always verify against your specific unit.

I/O Board Capacitors

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The I/O board contains smaller electrolytic capacitors that should be inspected and replaced if showing signs of aging:

I/O Board Capacitors
Typical Values Voltage Notes
10µF 16V Various locations
22µF 16V Near clock circuits
47µF 16V Near power input
100µF 16V Filter capacitors

CPU Board Capacitors

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The CPU board also contains electrolytic capacitors:

CPU Board Capacitors
Typical Values Voltage Notes
10µF 16V Various locations
47µF 16V Near voltage regulators
100µF 10V or 16V Power filtering

Analog Board Capacitors

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The CRT analog board contains both electrolytic and high-voltage capacitors:

Common capacitors include:

  • Small signal electrolytics (1µF – 100µF at 16V–50V)
  • Filter capacitors near horizontal and vertical deflection circuits
  • High-voltage capacitors in the flyback circuit (leave to professionals if uncertain)

Capacitor Replacement Procedure

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  1. Discharge and Prepare — Unplug Lisa; wait 24+ hours; discharge CRT if accessing analog board
  2. Document Original Layout — Photograph capacitor positions and orientations before removal
  3. Remove Boards — Remove the power supply or board being serviced
  4. Desolder Old Capacitors — Use a temperature-controlled iron; remove old solder
  5. Clean Pads — Use solder wick and isopropyl alcohol to clean pads
  6. Install New Capacitors — Observe correct polarity (stripe = negative on electrolytics)
  7. Solder Securely — Use quality solder; avoid cold joints
  8. Inspect Work — Check for solder bridges; verify polarity
  9. Test Voltages — Before reconnecting to system, verify power supply outputs if applicable
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  • Temperature-controlled soldering iron (adjustable to 700°F / 370°C)
  • Desoldering pump or solder wick
  • Fine leaded solder (0.5 mm diameter)
  • Isopropyl alcohol (90%+) and ESD-safe brush
  • Digital multimeter
  • Safety glasses
  • Heat-resistant gloves

Voltage Verification After Recap

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After power supply recap, measure output voltages before reconnecting to logic boards:

  • +5V rail: 4.85V – 5.15V
  • +12V rail: 11.9V – 12.7V
  • -12V rail: Within 5% of nominal

ProFile Drive Power Supply

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If you have a ProFile external hard drive, its power supply also contains RIFA capacitors and electrolytics that require replacement:

  • RIFA safety capacitors (same X2 replacements as Lisa PSU)
  • Electrolytic filter capacitors
  • The ProFile is prone to the same RIFA failures as the Lisa

Additional Tips

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  • Use high-quality Japanese brand capacitors (Nichicon, Panasonic, Rubycon)
  • Match or exceed original voltage ratings
  • Observe temperature ratings—use 105°C rated capacitors for power supply work
  • Take photos before and after for documentation
  • Keep a log of parts used for future reference
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