Commodore 64C Capacitor Replacement Guide

Replacing the electrolytic capacitors (recapping) in your Commodore 64C is a vital preventative measure to ensure stable operation, clear video and audio output, and long-term reliability. As these components age, they can cause erratic behaviour, power instability, video artefacts, and leackage. Recapping your 64C restores original performance and protects the chips from power-related faults.

Visual Inspection & Failure Signs

Before recapping, examine all electrolytic capacitors for these common failure indicators:

Bulging or domed tops – Indicates internal gas pressure and imminent failure.
Leaking electrolyte – Brown, green, or white residue at the base of the capacitor.
Corrosion or PCB staining – Green/black marks or discolouration around pads.
Unusual behaviour – Audio hum, video glitches, or random resets can often be traced to failing capacitors.

If any capacitor shows signs of distress, it is strongly recommended to replace all electrolytic capacitors on the board.

Commodore 64C Capacitor List

The Commodore 64C (board Assy 250469 and variants) uses a revised, cost-reduced PCB with fewer and smaller electrolytic capacitors compared to earlier C64 models. Always cross-check values with your board’s silkscreen, as minor revisions exist.

**Commodore 64C (Assy 250469) Electrolytic Capacitors**
Ref	Capacitance	Voltage	Circuit / Rail	Notes
C88	2,200 µF	10 V	Main +5 V bulk	Main filter for logic supply
C89	1,000 µF	10 V	VIC-II local decoupling	Sits near video chip (8565/8562)
C90	330 µF	10 V	SID 8580 analogue +9 V	Audio rail filter
C91	–	–	–	Not fitted (12 V rail deleted)
C15	10 µF	16 V	Reset RC timer	Ensures reliable power-on reset
C38	47 µF	16 V	Audio DC block	Lower value for 8580 SID bias
C70	2.2 µF	50 V	Chroma coupling (RF modulator)	Small foil can, optional if modulator removed
C71, C72	47 µF	16 V	RF modulator 5 V/audio buffer	Two cans inside modulator can

If your board is a rare 250469-Aldi variant with a 6581 SID, it may include C92 (470 µF, 16 V) for a linear 12 V regulator. Replace this if present.

SMD Capacitors

The standard 64C PCB does not use SMD electrolytics; all are through-hole types. If you encounter SMD cans, your board may be a late third-party or repair replacement—verify values before ordering.

Capacitor Replacement Procedure

Disassemble the C64C – Remove case screws (three at rear, two under keyboard), gently lift the keyboard, and unplug the LED and keyboard connectors.
Remove the RF shield – Desolder or carefully unclip the folded metal tabs. Set aside for reassembly.
Document capacitor positions – Take photos or label wires if unsure.
Desolder old capacitors – Use solder wick and flux. Commodore used high-melting-point solder; set your iron to at least 375 °C. Be patient with ground planes.
Clean pads – Remove any residual solder and clean with isopropyl alcohol.
Install new capacitors – Match polarity (long lead = positive) and ensure correct lead spacing (5 mm or 7.5 mm). Keep capacitor height below 17 mm for shield clearance.
Inspect work – Check for solder bridges or cold joints.
Reassemble and test – Refit the shield, reconnect keyboard and LED, and close the case.

Recommended Tools & Parts

Temperature-controlled soldering iron (70 W, 2 mm chisel tip)
Solder wick and desoldering pump
Leaded 63/37 or quality lead-free solder
105 °C, low-ESR radial capacitors (brands: Nichicon PW/PS, Panasonic FR/FC, Rubycon ZLH)
Isopropyl alcohol (IPA) and nylon brush
Kapton tape (to insulate capacitors near the RF shield)
Multimeter (for continuity and voltage checks)
Protective eyewear

Post-Recap Voltage & Ripple Checks

After recapping, verify the main power rails with a multimeter or oscilloscope:

**Commodore 64C Power Rails (No Cartridge, BASIC READY)**
Test Point	Expected Voltage	Max Ripple (p-p)
+5 V (PLA pin 24)	4.95 – 5.10 V	< 50 mV
+9 V (SID 8580 pin 28)	8.7 – 9.3 V	< 100 mV
9 VAC (user port pins 10/11)	8.5 – 10 V rms	Sine-like

If you observe video shimmer, audio buzz, or random resets, recheck your soldering and capacitor polarity. Ripple above 100 mV on any rail indicates a possible fault.

Additional Tips

Test your power supply first – A faulty “brick” can destroy new capacitors and chips.
Keep capacitor diameter similar – Especially for C89 and C90, as the RF shield may press against them.
RF modulator removal – If you have performed a composite/S-video mod and removed the RF modulator, C70, C71, and C72 may be omitted.
Reseat socketed chips – After recapping, temperature changes may unseat the VIC-II, SID, or PLA.
Store your C64C in a dry environment – Moisture accelerates capacitor degradation.
Dispose of old capacitors responsibly – Use an electronics recycling facility.

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