Commodore 64
ASSY 250425 — Standard breadbin "long board"
Summary
By the 250425, Commodore had replaced most of the 10 uF decoupling electrolytics with ceramics, so this board needs only six replacement cans. It is the quickest C64 long board to recap.
Safety & Warnings
Test the power supply first
A recap will not protect the machine from an original Commodore "black wedge" or beige brick. These fail with the 5 V rail drifting high and take out RAM, the CIAs, the PLA and the SID. Measure the 5 V rail under load before you fit a single new capacitor, and replace the brick with a modern regulated supply.
Confirm polarity against the board, not just the silkscreen
Align the negative stripe on each capacitor with the negative marking on the PCB. Commodore silkscreens of this era are occasionally ambiguous or reversed, so if a marking looks wrong, buzz the pad out to the ground plane with a continuity tester before soldering.
Higher voltage ratings are always safe
You can fit a higher voltage rating than original (25 V or 35 V in place of a 16 V part) as long as the can physically fits. Never fit a lower rating. Capacitance should stay at the original value.
Some C64 production runs used 50 V capacitors where the schematics call for 25 V. Either is correct; the values below follow the schematics.
The short list is not an omission. Commodore genuinely deleted most of the 10 uF decouplers on this revision - if your board has electrolytics at designators not listed here, note them and measure before assuming the list is incomplete.
Function and rail annotations are only shown on rows where the service manual or schematic confirms them.
Is This Your Board?
- The assembly number is silkscreened on the mainboard, usually near the cartridge port. Look for "ASSY 250425".
- Eight 4164 DRAM chips and an 8-pin video connector, like the 250407 - the silkscreen is what separates them.
- Quick confirmation: this board has far fewer electrolytic cans than a 250407. If you can count a dozen or more small radials, you are looking at an earlier revision.
- The 250425 has no C200. If a 2.2 uF sits at C200 near the video circuitry, your board is a 250466.
Verified rows are agreed by two or more independent sources. Check rows are revision-dependent or single-sourced — confirm the value against your own board before ordering.
Mainboard
| Ref | Value | Voltage | Type | Notes | Confidence |
|---|---|---|---|---|---|
C13 |
10 uF | 25 V | Radial | Verified | |
C19 |
2200 uF | 16 V | Axial | Largest can on the board. | Verified |
C24 |
22 uF | 25 V | Radial | 22 uF here, not the 10 uF fitted at C24 on the earlier long boards. | Verified |
C88 |
1000 uF | 25 V | Axial | Verified | |
C90 |
470 uF | 25 V | Axial | Verified | |
C91 |
100 uF | 16 V | Radial | Verified |
Extra Parts (not failure items)
These are not electrolytic recap candidates. They are listed because the kit vendors include them for a known modification or fix — do not replace them as part of a routine recap.
| Ref | Value | Voltage | Type | Purpose | Notes |
|---|---|---|---|---|---|
C38 |
4.7 nF | - | Ceramic | RESTORE key fix | Not an electrolytic and not a failure item. Replacing the original 51 pF with 4.7 nF restores the soft-touch RESTORE key function. Both cap-kit vendors include this part for exactly that reason. |
Mainboard — shopping list
- 1 x 10 uF 25 V Radial
- 1 x 2200 uF 16 V Axial
- 1 x 22 uF 25 V Radial
- 1 x 1000 uF 25 V Axial
- 1 x 470 uF 25 V Axial
- 1 x 100 uF 16 V Radial
Recap Tips
- Six capacitors makes this a 30-minute job. Do not let that tempt you into skipping the power supply check first.
- Use 105 C low-ESR parts. Panasonic FR or FC and Nichicon PW or HE series are the usual bench choices.
- Check can diameter before ordering - the 2200 uF axial at C19 and the 1000 uF at C88 have to clear the RF shield and the case.
- While the board is out, reflow the power connector and RF modulator joints. They crack from decades of plug cycles.
Related Symptoms
- Black screen / no video Work the power rail tests first; a capacitor is rarely the cause of a hard no-boot.
- Garbage video / character corruption Usually DRAM or the PLA on a long board rather than a capacitor.
Sources & References
- Console5 TechWiki - Commodore 64 Per-assembly capacitor lists compiled from real boards and later schematics.
- Retro Rewind - C64 Assembly 250425 Cap List Independent list that agrees with Console5 on every row used here.
- Commodore 64 Service Manual (PDF) Primary reference for the official parts lists.