Commodore 64 Capacitor Replacement Guide - Revision history

Josh: /* Recommended Tools & Parts */

2025-05-17T23:20:00Z

Recommended Tools & Parts

← Older revision		Revision as of 00:20, 18 May 2025
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	* '''Socket inspection :''' reseat VIC-II, SID, PLA after the recap – temperature swings often unseat them.		* '''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.		* '''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 ==		== Related Pages ==

94.134.53.141: Quality capacitors hint

2025-05-17T19:54:40Z

Quality capacitors hint

← Older revision		Revision as of 20:54, 17 May 2025
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	* Leaded 63/37 or SAC-lead-free solder (avoid cheap flux-core that leaves residue).		* 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).		* '''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.		* IPA, nylon brush, Kapton tape to insulate cap cans that sit against the RF shield.

Josh at 07:39, 12 May 2025

2025-05-12T07:39:53Z

Josh: Created page with " '''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.''' 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 w..."

2025-04-24T12:01:11Z

Created page with "<templatestyles src="Template:StyledTable/styles.css" /> '''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.''' 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 w..."

New page

<templatestyles src="Template:StyledTable/styles.css" />

'''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.'''
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 ==
* '''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.

== 📋 Commodore 64 Logic-Board Capacitor Lists ==
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 ===
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''Early C64 Electrolytic Capacitors'''
! Board ref !! Capacitance !! Voltage !! Purpose / rail
|-
| C88 || 4 700 µF || 16 V || Main +5 V bulk (from external PSU)
|-
| C90 || 1 000 µF || 16 V || Secondary 5 V at VIC/SID (reduces raster-noise)
|-
| C91 || 470 µF || 25 V || +12 V filter (SID 6581 & VIC 6567/9 analogue)
|-
| C13 || 220 µF || 25 V || 9 VAC ► +12 V doubler reservoir
|-
| C14 || 100 µF || 16 V || 9 VAC ► 5 V gate-array supply (PLA decouple)
|-
| C15 || 10 µF || 16 V || Power-on reset RC
|-
| C38 || 22 µF || 16 V || Audio path (SID DC-blocking)
|-
| C70 || 3.3 µF || 50 V || Chroma-coupling into RF modulator
|-
| C71,C72 || 100 µF || 16 V || RF modulator 5 V and audio buffer
|}

''Very early NTSC boards mark C90 as 2 200 µF – Commodore standardised on 1 000 µF by Rev-B.''

=== 🖥️ Assy 250425 – first “cost-reduced” long board ===
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:center;"
|+'''250466 Capacitors'''
! Ref !! Capacitance !! Voltage !! Notes
|-
| C88 || 3 300 µF || 16 V || Commodore shaved value; 4 700 µF fits & improves ripple
|-
| C90 || 470 µF || 16 V || Lower current draw of HMOS chips allowed smaller part
|-
| C91 || 220 µF || 25 V || +12 V still present for 6581 SID (last board to use it)
|-
| Others || identical || – || Replace like-for-like
|}

=== 💾 “Short boards” – Assy 250469 (A/B/C) & 250469-Aldi ===
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''Short-Board Capacitor Set'''
! Ref !! Capacitance !! Voltage !! Rail / circuit
|-
| C88 || 2 200 µF || 10 V || Bulk +5 V (HMOS load ≈ 600 mA)
|-
| C89 || 1 000 µF || 10 V || Local decouple for VIC-II (8562/8565)
|-
| C90 || 330 µF || 10 V || SID 8580 analogue +9 V
|-
| C91 || *n/a* || – || 12 V rail deleted; do '''not''' fit tall cans!
|-
| C15 || 10 µF || 16 V || Reset timer (value unchanged)
|-
| C38 || 47 µF || 16 V || Audio DC-block (lower because 8580 output bias differs)
|-
| C70 || 2.2 µF || 50 V || Chroma-coupling (smaller foil can type)
|-
| C71,C72 || 47 µF || 16 V || RF modulator local filters
|}

''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.''

== 🛠️ Recapping Procedure ==
# '''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 ==
{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+'''Expected Rails – BASIC READY prompt, no cartridge'''
! Test point (scope @20 MHz) !! Long board !! Short board !! Max ripple (p-p)
|-
| +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
|-
| +9 V (SID pin 28, 8580) || – || 8.7 – 9.3 V || < 100 mV
|-
| 9 VAC (user-port pins 10/11) || 8.5 – 10 V rms || same || sine-like
|}

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

== 🧰 Recommended Tools & Parts ==
* 70 W temperature-controlled iron (2 mm chisel tip).
* Solder-wick '''and''' spring pump – double-layer ground pads are stubborn.
* 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).
* IPA, nylon brush, Kapton tape to insulate cap cans that sit against the RF shield.

== 💡 Extra Tips ==
* '''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.

== 🔗 Related Pages ==
* [[Commodore 64 Troubleshooting Guide]]
* [[Commodore 64C Troubleshooting Guide]]
* [[Commodore 64 Power-Supply Protector (C64 Saver)]]

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

← Older revision		Revision as of 08:39, 12 May 2025
Line 4:		Line 4:
	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.		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 ==		== Visual Inspection & Failure Signs ==
	* '''Bulging or leaning cans''' – especially the tall 4 700 µF reservoir (C88/C89).		* '''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.		* '''Leakage residue''' – brown/green crust at base of C90 (colour-RAM decoupler) is common.
Line 12:		Line 12:
	If '''one''' capacitor shows trouble, replace '''all''' electrolytics on the board.		If '''one''' capacitor shows trouble, replace '''all''' electrolytics on the board.

	== 📋 Commodore 64 Logic-Board Capacitor Lists ==		== Commodore 64 Logic-Board Capacitor Lists ==
	Unlike the VIC-20, the C64 underwent five major PCB generations. Commodore kept reference numbers fairly consistent, but always cross-check your silkscreen.		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 ===		=== “Long boards” – Assy 326298 / 250407 ===
	{\| class="wikitable styled-table" style="width:100%; text-align:center;"		{\| class="wikitable styled-table" style="width:100%; text-align:center;"
	\|+'''Early C64 Electrolytic Capacitors'''		\|+'''Early C64 Electrolytic Capacitors'''
Line 41:		Line 41:
	''Very early NTSC boards mark C90 as 2 200 µF – Commodore standardised on 1 000 µF by Rev-B.''		''Very early NTSC boards mark C90 as 2 200 µF – Commodore standardised on 1 000 µF by Rev-B.''

	=== 🖥️ Assy 250425 – first “cost-reduced” long board ===		=== Assy 250425 – first “cost-reduced” long board ===
	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.		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) ===		=== Assy 250466 – transitional board (8-chip DRAM → 2-chip DRAM) ===
	{\| class="wikitable styled-table" style="width:100%; text-align:center;"		{\| class="wikitable styled-table" style="width:100%; text-align:center;"
	\|+'''250466 Capacitors'''		\|+'''250466 Capacitors'''
Line 58:		Line 58:
	\|}		\|}

	=== 💾 “Short boards” – Assy 250469 (A/B/C) & 250469-Aldi ===		=== “Short boards” – Assy 250469 (A/B/C) & 250469-Aldi ===
	{\| class="wikitable styled-table" style="width:100%; text-align:center;"		{\| class="wikitable styled-table" style="width:100%; text-align:center;"
	\|+'''Short-Board Capacitor Set'''		\|+'''Short-Board Capacitor Set'''
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	''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.''		''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.''

	== 🛠️ Recapping Procedure ==		== Recapping Procedure ==
	# '''Disassemble :''' remove three rear screws, two under the keyboard, pop keyboard hinges.		# '''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.		# '''Remove RF shield :''' desolder the six folded-tabs or snip and replace with screws on re-assembly.
Line 91:		Line 91:
	# First power-up through a current-limited bench supply or a '''C64 Saver''' inline protector in case the original brick is bad.		# 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 ==		== Post-Recap Voltage / Ripple Checks ==
	{\| class="wikitable styled-table" style="width:80%; text-align:center;"		{\| class="wikitable styled-table" style="width:80%; text-align:center;"
	\|+'''Expected Rails – BASIC READY prompt, no cartridge'''		\|+'''Expected Rails – BASIC READY prompt, no cartridge'''
Line 107:		Line 107:
	''A VIC-II picture that jitters or vertical “rainbow lines” usually means > 150 mV of 5 V ripple.''		''A VIC-II picture that jitters or vertical “rainbow lines” usually means > 150 mV of 5 V ripple.''

	== 🧰 Recommended Tools & Parts ==		== Recommended Tools & Parts ==
	* 70 W temperature-controlled iron (2 mm chisel tip).		* 70 W temperature-controlled iron (2 mm chisel tip).
	* Solder-wick '''and''' spring pump – double-layer ground pads are stubborn.		* Solder-wick '''and''' spring pump – double-layer ground pads are stubborn.
Line 114:		Line 114:
	* IPA, nylon brush, Kapton tape to insulate cap cans that sit against the RF shield.		* IPA, nylon brush, Kapton tape to insulate cap cans that sit against the RF shield.

	== 💡 Extra Tips ==		== Extra Tips ==
	* '''Check the brick first !''' An over-voltage PSU kills fresh caps (and PLA / RAM) instantly.		* '''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.		* '''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.
Line 121:		Line 121:
	* '''Re-cap the 1541-II brick''' if bundled; its 4 700 µF can is the same age.		* '''Re-cap the 1541-II brick''' if bundled; its 4 700 µF can is the same age.

	== 🔗 Related Pages ==		== Related Pages ==
	* [[Commodore 64 Troubleshooting Guide]]		* [[Commodore 64 Troubleshooting Guide]]
	* [[Commodore 64C Troubleshooting Guide]]		* [[Commodore 64C Troubleshooting Guide]]
Line 127:		Line 127:

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