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Commodore 64 Capacitor Replacement Guide

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Revision as of 22:01, 21 September 2026 by Josh (talk | contribs) (Point citations at the existing service manual page rather than the duplicate)

Recapping a Commodore 64 restores stable supply rails, reduces heat stress on the MOS custom chips and cures a specific family of warm-up faults that Commodore itself documented.

Every value on this page is taken from Commodore's own parts lists in the C64 / C64C Service Manual (March 1992).[1] Cross-check against your own board's silkscreen before ordering — Commodore changed values between revisions, and boards were built with substitutions.

⚠️ A correction

An earlier version of this page listed C88 as 4700 µF 16 V, C90 as 1000 µF 16 V and C91 as 470 µF 25 V. None of those values appears in any Commodore parts list, the roles were transposed, and the voltage ratings were specified below the rails those capacitors sit on. If you recapped a C64 from this page before September 2026, check what you fitted against the tables below.

Which board do you have?

The assembly number is silkscreened on the board. Commodore's own cross-reference:[1]

C64 mainboard revisions
Revision Assembly Notes
Original 326298-01 5-pin video connector, "long board"
A (CR) 250407-01 / -04 8-pin video connector, long board
B 250425-01 Long board, cost-reduced
B3 250466-01 C64-B3
E 250469-01 C64-E "short board" — also used in the Commodore 64C

Electrolytic capacitors by board revision

These are the electrolytics — the parts that age. Ceramic and mica capacitors on these boards do not normally need replacing and are not listed.

326298-01 — original long board

326298-01 electrolytics[1]
Ref Value Rating Tolerance Function
C19 2200 µF 16 V Main supply reservoir
C88 470 µF 50 V Supply filtering
C90 470 µF 50 V Supply filtering
C91 100 µF 16 V Regulator decoupling
C8, C12–C15, C17, C24, C34, C57, C62, C64, C65, C94, C102 10 µF 25 V +50 % / −10 % General decoupling

250407-04 — 8-pin long board

250407-04 electrolytics[1]
Ref Value Rating Tolerance Function
C19 2200 µF 16 V Main supply reservoir
C88 1000 µF 25 V Supply filtering
C90 470 µF 50 V Supply filtering
C91 100 µF 16 V +50 % / −10 % Regulator decoupling
C8, C13–C15, C17, C24, C34, C57, C62, C65, C94, C102 10 µF 25 V +50 % / −10 % General decoupling
C108 10 µF 25 V 20 %

250425-01

250425-01 electrolytics[1]
Ref Value Rating Tolerance Function
C19 2200 µF 16 V Main supply reservoir
C88 1000 µF 25 V Supply filtering
C90 470 µF 50 V Supply filtering
C91 100 µF 16 V +50 % / −10 % Regulator decoupling
C13 10 µF 25 V +50 % / −10 % Decoupling
C24 22 µF 25 V +50 % / −10 % Decoupling
C15 4.7 µF 16 V 20 % Tantalum — replace with tantalum

250466-01 — C64-B3

Commodore part numbers are given here because this list prints them.[1]

250466-01 electrolytics[1]
Ref Value Rating Package Commodore part no.
C19 2200 µF 16 V Axial 900101-33
C88 1000 µF 25 V Axial 900101-50
C90 470 µF 25 V Axial 900101-49
C91 100 µF 16 V Radial 900100-40
C13 (C210) 10 µF 25 V Radial 900100-01 (sub 251079-16, 20 %)
C24 22 µF 25 V Radial 900100-24
C200 2.2 µF Radial 251079-06
C15 4.7 µF 16 V Radial 900410-13 — tantalum, 20 %
C20 0.2 µF 100 V Radial 251875-01 — film, 20 %

Note the C90 rating change. It is 50 V on the 250407 and 250425 boards and 25 V on the 250466. Either will work electrically; fit at least the rating printed for your board.

The service manual's troubleshooting table names capacitors directly for two symptoms. Both are worth knowing before you assume a chip has failed:[1]

Symptoms Commodore attributes to capacitors[1]
Symptom Commodore's check
Intermittent display C88 — noted as a possible bad connection rather than a failed part, so reflow the joints before replacing it
Black band scrolling through the screen once the system warms up External power supply; C90, C88, CR4; VR2 (5 V regulator)
White band scrolling down the screen (60 Hz hum) External power supply; VR2 (5 V regulator)

That second row is the classic C64 recap symptom, and Commodore's own ordering is worth following: check the external supply first. The C64's 5 V rail comes in already regulated from the brick, and a failing brick produces the same scrolling band as tired board electrolytics.

Before you start

  • The power brick is the prime suspect in any C64 power fault. The original supplies are notorious for drifting high as they age and taking the MOS chips with them. Measure the 5 V output under load before blaming the board.
  • Work from your board's own silkscreen. Commodore substituted parts freely; the assembly number tells you which list applies, but the board is the final authority.
  • Anti-static precautions throughout — the 6510, VIC-II, SID and PLA are irreplaceable in practical terms.
  • See Capacitor Failure Symptoms for recognising a failed part, and Recommended Tools for the workshop kit.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at Commodore 64 / 64C Service Manual. Component-level parts lists give capacitance, voltage rating, tolerance and Commodore part number for every capacitor on each mainboard revision, and the manual carries Commodore's own symptom-to-component troubleshooting table.
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