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Rewrite from Commodore's own service manual parts lists: previous values (C88 4700uF/16V, C90 1000uF/16V, C91 470uF/25V) matched no Commodore list and under-specified voltage ratings. Banner removed; page now fully cited.
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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.


'''Recapping a Commodore 64 (all board revisions) restores stable power rails, lowers heat-stress on MOS chips and cures many “mystery” crashes, video glitches and SID noise.''' 
'''Every value on this page is taken from Commodore's own parts lists''' in the [[Commodore C64 Service Manual|C64 / C64C Service Manual]] (March 1992).<ref name="sm">Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at [[Commodore C64 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.</ref> Cross-check against your own board's silkscreen before ordering — Commodore changed values between revisions, and boards were built with substitutions.
Because every C64 relies on an external '''+5 V DC / 9 VAC “brick”''' the on-board capacitors don’t fail quite as catastrophically as in computers with internal switch-modes, yet forty-year-old aluminium electrolytics are now well past their design life.


== Visual Inspection & Failure Signs ==
== ⚠️ A correction ==
* '''Bulging or leaning cans''' – especially the tall 4 700 µF reservoir (C88/C89). 
* '''Leakage residue''' – brown/green crust at base of C90 (colour-RAM decoupler) is common. 
* '''Ripple / hum on audio''' – audible buzz that follows screen brightness often tracks to dried-out C13 (SID analogue rail) or the RF-modulator’s 100 µF pair. 
* '''Intermittent reset when warm''' – C15 (10 µF reset RC) high-ESR causes POR threshold to mis-trip.


If '''one''' capacitor shows trouble, replace '''all''' electrolytics on the board.
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.


== Commodore 64 Logic-Board Capacitor Lists ==
== Which board do you have? ==
Unlike the VIC-20, the C64 underwent five major PCB generations.  Commodore kept reference numbers fairly consistent, but always cross-check your silkscreen.


=== “Long boards” – Assy 326298 / 250407 ===
The assembly number is silkscreened on the board. Commodore's own cross-reference:<ref name="sm">Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at [[Commodore C64 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.</ref>
{| class="wikitable styled-table" style="width:100%; text-align:center;"
 
|+'''Early C64 Electrolytic Capacitors'''
{| class="wikitable styled-table" style="width:100%; text-align:left;"
! Board ref !! Capacitance !! Voltage !! Purpose / rail
|+'''C64 mainboard revisions'''
! Revision !! Assembly !! Notes
|-
|-
| C88 || 4 700 µF || 16 V || Main +5 V bulk (from external PSU)
| Original || '''326298-01''' || 5-pin video connector, "long board"
|-
|-
| C90 || 1 000 µF || 16 V || Secondary 5 V at VIC/SID (reduces raster-noise)
| A (CR) || '''250407-01 / -04''' || 8-pin video connector, long board
|-
|-
| C91 || 470 µF || 25 V || +12 V filter (SID 6581 & VIC 6567/9 analogue)
| B || '''250425-01''' || Long board, cost-reduced
|-
|-
| C13 || 220 µF || 25 V || 9 VAC ► +12 V doubler reservoir
| B3 || '''250466-01''' || C64-B3
|-
|-
| C14 || 100 µF || 16 V || 9 VAC ► 5 V gate-array supply (PLA decouple)
| 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 ===
 
{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''326298-01 electrolytics'''<ref name="sm">Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at [[Commodore C64 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.</ref>
! Ref !! Value !! Rating !! Tolerance !! Function
|-
|-
| C15 || 10 µF || 16 V || Power-on reset RC
| '''C19''' || 2200 µF || 16 V || || Main supply reservoir
|-
|-
| C38 || 22 µF || 16 V || Audio path (SID DC-blocking)
| '''C88''' || 470 µF || 50 V || || Supply filtering
|-
|-
| C70 || 3.3 µF || 50 V || Chroma-coupling into RF modulator
| '''C90''' || 470 µF || 50 V || || Supply filtering
|-
|-
| C71,C72 || 100 µF || 16 V || RF modulator 5 V and audio buffer
| '''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
|}
|}


''Very early NTSC boards mark C90 as 2 200 µF – Commodore standardised on 1 000 µF by Rev-B.''
=== 250407-04 — 8-pin long board ===
 
{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''250407-04 electrolytics'''<ref name="sm">Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at [[Commodore C64 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.</ref>
! 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 % ||
|}


=== Assy 250425 – first “cost-reduced” long board ===
=== 250425-01 ===
Same parts list as 250407 '''except''' C91 is omitted (12 V rail deleted when 8580 SID not yet adopted but cost saving began).  Replace values exactly as found.


=== Assy 250466 – transitional board (8-chip DRAM → 2-chip DRAM) ===
{| class="wikitable styled-table" style="width:100%; text-align:left;"
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''250425-01 electrolytics'''<ref name="sm">Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at [[Commodore C64 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.</ref>
|+'''250466 Capacitors'''
! Ref !! Value !! Rating !! Tolerance !! Function
! Ref !! Capacitance !! Voltage !! Notes
|-
| '''C19''' || 2200 µF || 16 V || || Main supply reservoir
|-
|-
| C88 || 3 300 µF || 16 V || Commodore shaved value; 4 700 µF fits & improves ripple
| '''C88''' || 1000 µF || 25 V || || Supply filtering
|-
|-
| C90 || 470 µF || 16 V || Lower current draw of HMOS chips allowed smaller part
| '''C90''' || 470 µF || 50 V || || Supply filtering
|-
|-
| C91 || 220 µF || 25 V || +12 V still present for 6581 SID (last board to use it)
| '''C91''' || 100 µF || 16 V || +50 % / −10 % || Regulator decoupling
|-
|-
| Others || identical || – || Replace like-for-like
| 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
|}
|}


=== “Short boards” – Assy 250469 (A/B/C) & 250469-Aldi ===
=== 250466-01 — C64-B3 ===
{| class="wikitable styled-table" style="width:100%; text-align:center;"
 
|+'''Short-Board Capacitor Set'''
Commodore part numbers are given here because this list prints them.<ref name="sm">Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at [[Commodore C64 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.</ref>
! Ref !! Capacitance !! Voltage !! Rail / circuit
 
{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''250466-01 electrolytics'''<ref name="sm">Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at [[Commodore C64 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.</ref>
! Ref !! Value !! Rating !! Package !! Commodore part no.
|-
|-
| C88 || 2 200 µF || 10 V || Bulk +5 V (HMOS load ≈ 600 mA)
| '''C19''' || 2200 µF || 16 V || Axial || 900101-33
|-
|-
| C89 || 1 000 µF || 10 V || Local decouple for VIC-II (8562/8565)
| '''C88''' || 1000 µF || 25 V || Axial || 900101-50
|-
|-
| C90 || 330 µF || 10 V || SID 8580 analogue +9 V
| '''C90''' || '''470 µF''' || '''25 V''' || Axial || 900101-49
|-
|-
| C91 || *n/a* || – || 12 V rail deleted; do '''not''' fit tall cans!
| '''C91''' || 100 µF || 16 V || Radial || 900100-40
|-
|-
| C15 || 10 µF || 16 V || Reset timer (value unchanged)
| C13 (C210) || 10 µF || 25 V || Radial || 900100-01 (sub 251079-16, 20 %)
|-
|-
| C38 || 47 µF || 16 V || Audio DC-block (lower because 8580 output bias differs)
| C24 || 22 µF || 25 V || Radial || 900100-24
|-
|-
| C70 || 2.2 µF || 50 V || Chroma-coupling (smaller foil can type)
| C200 || 2.2 µF || || Radial || 251079-06
|-
|-
| C71,C72 || 47 µF || 16 V || RF modulator local filters
| '''C15''' || 4.7 µF || 16 V || Radial || 900410-13 — '''tantalum''', 20 %
|-
| C20 || 0.2 µF || 100 V || Radial || 251875-01 — film, 20 %
|}
|}


''The 250469-Aldi variant adds a linear 7812 + 470 µF 16 V can (C92) to power a 6581 SID on an otherwise 5 V-only board. If present, replace that extra capacitor as well.''
'''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.


== Recapping Procedure ==
== Commodore's own capacitor-related faults ==
# '''Disassemble :''' remove three rear screws, two under the keyboard, pop keyboard hinges. 
# '''Remove RF shield :''' desolder the six folded-tabs or snip and replace with screws on re-assembly. 
# '''Label keyboard & LED leads.''' 
# Desolder each capacitor with braid + flux.  Commodore used thick, high-temperature solder; '''375 °C''' is usually required. 
# Fit new capacitors, matching '''polarity and lead-spacing''' (5 mm on small cans, 7.5 mm on main filters).  Keep height ≤ 17 mm so the metal shield clears. 
# Clean flux, inspect for bridges. 
# First power-up through a current-limited bench supply or a '''C64 Saver''' inline protector in case the original brick is bad.


== Post-Recap Voltage / Ripple Checks ==
The service manual's troubleshooting table names capacitors directly for two symptoms. Both are worth knowing before you assume a chip has failed:<ref name="sm">Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at [[Commodore C64 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.</ref>
{| class="wikitable styled-table" style="width:80%; text-align:center;"
 
|+'''Expected Rails – BASIC READY prompt, no cartridge'''
{| class="wikitable styled-table" style="width:100%; text-align:left;"
! Test point (scope @20 MHz) !! Long board !! Short board !! Max ripple (p-p)
|+'''Symptoms Commodore attributes to capacitors'''<ref name="sm">Commodore Business Machines, C64 / C64C Service Manual, March 1992, hosted at [[Commodore C64 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.</ref>
|-
! Symptom !! Commodore's check
| +5 V (U6 PLA pin 24) || 4.95 – 5.10 V || same || < 50 mV
|-
|-
| +12 V (SID pin 28) || 11.5 – 12.6 V || – || < 120 mV
| '''Intermittent display''' || '''C88''' — noted as a possible bad connection rather than a failed part, so reflow the joints before replacing it
|-
|-
| +9 V (SID pin 28, 8580) || – || 8.7 – 9.3 V || < 100 mV
| '''Black band scrolling through the screen once the system warms up''' || External power supply; '''C90, C88''', CR4; VR2 (5 V regulator)
|-
|-
| 9 VAC (user-port pins 10/11) || 8.5 – 10 V rms || same || sine-like
| White band scrolling down the screen (60 Hz hum) || External power supply; VR2 (5 V regulator)
|}
|}


''A VIC-II picture that jitters or vertical “rainbow lines” usually means > 150 mV of 5 V ripple.''
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.
 
== Related pages ==


== Recommended Tools & Parts ==
* [[Commodore 64]] · [[Commodore 64C]] · [[Commodore 64 General Maintenance]] · [[Commodore 64 Troubleshooting Guide]]
* 70 W temperature-controlled iron (2 mm chisel tip). 
* '''[[Commodore C64 Service Manual]]''' — the source for every value on this page
* Solder-wick '''and''' spring pump – double-layer ground pads are stubborn. 
* [[Capacitor Failure Symptoms]] · [[Recommended Tools]] · [[Battery Explosion, Capacitor or Corrosion Damage]]
* Leaded 63/37 or SAC-lead-free solder (avoid cheap flux-core that leaves residue). 
* '''105 °C, low-ESR''' radial capacitors (Nichicon PW/PS, Panasonic FR/FC, Rubycon ZLH). 
* ask an expert or the AI about specialty caps like polyester and hybrid types. These have many advantages like longer/unlimited life and less noise, especially with regard to the SID and VIC filters.
* IPA, nylon brush, Kapton tape to insulate cap cans that sit against the RF shield.


== Extra Tips ==
== References ==
* '''Check the brick first !''' An over-voltage PSU kills fresh caps (and PLA / RAM) instantly. 
* '''SID heat-pad :''' early boards rely on C90 as a “heat-sink standoff” – keep replacement can the same diameter so the RF-shield pad still contacts the SID. 
* '''Retain RF modulator?''' If you have done an S-video or composite-bypass mod, you may delete C70/71/72 and the entire modulator 5 V line. 
* '''Socket inspection :''' reseat VIC-II, SID, PLA after the recap – temperature swings often unseat them. 
* '''Re-cap the 1541-II brick''' if bundled; its 4 700 µF can is the same age.
* '''Ask an expert''' or the AI about specialty caps like '''polyester''' and '''hybrid''' types. These have many advantages like longer/unlimited life and less noise, especially with regard to the SID and VIC filters.


== Related Pages ==
<references />
* [[Commodore 64 Troubleshooting Guide]] 
* [[Commodore 64C Troubleshooting Guide]] 
* [[Commodore 64 Power-Supply Protector (C64 Saver)]] 


[[Category:Commodore Systems]]
[[Category:Commodore Systems]]
[[Category:Capacitor Replacement Guides]]
[[Category:Capacitor Replacement Guides]]

Revision as of 21:55, 21 September 2026

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 C64 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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