Commodore VIC-20 Capacitor Replacement Guide: Difference between revisions
Created page with "<templatestyles src="Template:StyledTable/styles.css" /> '''Replacing electrolytic capacitors (“recapping”) in a Commodore VIC-20 is one of the highest-impact reliability upgrades you can perform.''' A fresh capacitor set restores clean DC rails, reduces video noise, cures random resets, and protects rare MOS chips from over-ripple voltage spikes. == 🔍 Visual Inspection & Failure Signs == * '''Bulging tops''' – Any domed aluminium case is a near-certain fail..." |
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A fresh capacitor set restores clean DC rails, reduces video noise, cures random resets, and protects rare MOS chips from over-ripple voltage spikes. | A fresh capacitor set restores clean DC rails, reduces video noise, cures random resets, and protects rare MOS chips from over-ripple voltage spikes. | ||
== | == Visual Inspection & Failure Signs == | ||
* '''Bulging tops''' – Any domed aluminium case is a near-certain failure. | * '''Bulging tops''' – Any domed aluminium case is a near-certain failure. | ||
* '''Electrolyte residue''' – Brown crust or oily film at the capacitor base. | * '''Electrolyte residue''' – Brown crust or oily film at the capacitor base. | ||
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If '''any''' of the above are present – or if the machine is 40 years old and un-serviced – replace the full set. | If '''any''' of the above are present – or if the machine is 40 years old and un-serviced – replace the full set. | ||
== | == VIC-20 Logic-Board Capacitor Lists (by Assy #) == | ||
The VIC-20 | The VIC-20 has a single logic board the tables below contain all the replaceable capacitors. | ||
=== | === Early 2-Prong Board (Assy 324003 & “214003”) === | ||
{| class="wikitable styled-table" style="width:100%; text-align:center;" | {| class="wikitable styled-table" style="width:100%; text-align:center;" | ||
|+'''Early VIC-20 Capacitors''' | |+'''Early VIC-20 Capacitors''' | ||
! Board Ref !! Capacitance !! Voltage !! Purpose (rail / circuit) | ! Board Ref !! Capacitance !! Voltage !! Purpose (rail / circuit) | ||
|- | |- | ||
| C10 || 100 µF || 16 V || 9 VAC ► +5 V pre-reg filter | | C10 || 100 µF || 16 V || 9 VAC ► +5 V pre-reg filter | ||
|- | |- | ||
| C11 || 4 700 µF || 10 V || Main +5 V bulk filter | | C11 || 4 700 µF || 10 V || Main +5 V bulk filter | ||
|- | |- | ||
| C12 || 220 µF || 25 V || +12 V line for VIC analogue core | | C12 || 220 µF || 25 V || +12 V line for VIC analogue core | ||
|- | |- | ||
| C13 || 1 000 µF || 16 V || Secondary +5 V smoothing (regulator out) | | C13 || 1 000 µF || 16 V || Secondary +5 V smoothing (regulator out) | ||
|- | |- | ||
| C18 || 10 µF || 16 V || Power-on reset RC timer | | C18 || 10 µF || 16 V || Power-on reset RC timer | ||
|- | |- | ||
| C90 || 3.3 µF || 50 V || Audio-path coupling (VIC DAC) | | C90 || 3.3 µF || 50 V || Audio-path coupling (VIC DAC) | ||
|- | |- | ||
| C91 || 470 µF || 10 V || Datasette motor supply filter | | C91 || 470 µF || 10 V || Datasette motor supply filter | ||
|} | |} | ||
''Values mirror Commodore service-manual BOM; some very early 1981 PCBs mark C10/C12 as 35 V parts – 25 V or 35 V replacements are both acceptable.'' | |||
=== | === Cost-Reduced “VIC-20 CR” Board (Assy 250403) === | ||
{| class="wikitable styled-table" style="width:100%; text-align:center;" | {| class="wikitable styled-table" style="width:100%; text-align:center;" | ||
|+'''Cost-Reduced VIC-20 Capacitors''' | |+'''Cost-Reduced VIC-20 Capacitors''' | ||
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> '''Board markings vary.''' Commodore deleted the on-board 7805 on Assy 250403, so the '''4 700 µF can is absent'''; the largest can you will see is 1 000 µF. Always cross-check against your board silkscreen before ordering. | > '''Board markings vary.''' Commodore deleted the on-board 7805 on Assy 250403, so the '''4 700 µF can is absent'''; the largest can you will see is 1 000 µF. Always cross-check against your board silkscreen before ordering. | ||
== | == Recapping Procedure == | ||
# '''Disassemble''' – Remove six case screws, slide keyboard forward, lift the RF shield. | # '''Disassemble''' – Remove six case screws, slide keyboard forward, lift the RF shield. | ||
# '''Label cables''' – Photos help when reconnecting the power-LED & keyboard flex. | # '''Label cables''' – Photos help when reconnecting the power-LED & keyboard flex. | ||
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# '''Re-form (optional)''' – Bring the board up on a bench supply through a 1 Ω resistor for the first 30 s to reform large cans gently. | # '''Re-form (optional)''' – Bring the board up on a bench supply through a 1 Ω resistor for the first 30 s to reform large cans gently. | ||
== | == Post-Recap Voltage Checks == | ||
{| class="wikitable styled-table" style="width:75%; text-align:center;" | {| class="wikitable styled-table" style="width:75%; text-align:center;" | ||
|+'''Expected Rails (No-Cartridge, BASIC Prompt)''' | |+'''Expected Rails (No-Cartridge, BASIC Prompt)''' | ||
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|} | |} | ||
''An oscilloscope should show < 50 mV p-p ripple on +5 V after recap.'' | |||
== | == Recommended Tools & Parts == | ||
* 60 W temperature-controlled iron (fine conical tip) | * 60 W temperature-controlled iron (fine conical tip) | ||
* Desolder‐pump '''and''' braid – VIC pads lift easily if overheated. | * Desolder‐pump '''and''' braid – VIC pads lift easily if overheated. | ||
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== 🔗 Related Pages == | == 🔗 Related Pages == | ||
* [[Commodore VIC-20 General Maintenance Guide]] | * [[VIC-20 General Maintenance|Commodore VIC-20 General Maintenance Guide]] | ||
* [[Commodore VIC-20 Troubleshooting Guide]] | * [[VIC-20 Troubleshooting Guide|Commodore VIC-20 Troubleshooting Guide]] | ||
* [[CRT Discharge Procedure]] | * [[CRT Discharge Procedure]] | ||
[[Category:Commodore Systems]] | [[Category:Commodore Systems]] | ||
[[Category:Capacitor Replacement Guides]] | [[Category:Capacitor Replacement Guides]] | ||