Recap guide

Recap the Commodore 1541 and 1541-II drive

The 1541's power supply and big filter caps are the usual suspects, and one repair turned up a shorted filter cap. A shop page lists capacitors by board type, from Type 1 through the 1541-II.

Open the interactive checklist Tick off each capacitor as you replace it. It saves in your browser.

Worth a recap. Reports say it is a common and useful fix on this machine.

Which board do I have?

Boards changed during production. These notes come from the linked sources, and many are only partly documented, so check the board in front of you.

• 1541 original long board, assembly 1540001 (Medium confidence). How to tell: Check the assembly number printed on the board; the C64 Wiki describes the original 1541 as the larger board with internal power supply. Capacitors: Retailer list: C1 and C4 1uF radial, C2 and C5 47uF radial, C56 100uF radial, C65 220uF radial, C51 6800uF axial, C52 10000uF axial; motor board has 3x 10uF, 2x 4.7uF, 1x 2.2uF, 1x 1uF, 2x 0.47uF radial. Capacitor list differs from other revisions: yes. Source
• 1541 boards 1540048, 1540050 and 250442/46 (Medium confidence). How to tell: Assembly number on the board, per the retailer. Capacitors: C1 and C4 1uF, C2 and C5 47uF, C13 220uF radial, C16 4700uF axial, C17 6800uF axial, C46 100uF radial; motor board set as above. Capacitor list differs from other revisions: yes. Source
• 1541C boards 250448 and 251854 (Medium confidence). How to tell: Assembly number on the board; the 1541C is the shorter board with extra case vents. Capacitors: C1 and C2 1uF, C4, C6, C13 and C22 47uF radial, C7 4700uF axial, C8 6800uF axial; motor board set as above. Capacitor list differs from other revisions: yes. Source
• 1541-II, assembly 340503 (Medium confidence). How to tell: Redesigned board with an external 5V and 12V supply instead of an internal one. Capacitors: Mainboard 3x 10uF 25V radial; motor board 3x 10uF 35V, 2x 4.7uF 50V, 1x 2.2uF 50V, 1x 1uF 50V, 2x 0.47uF radial. The external supply is a separate recap job. Capacitor list differs from other revisions: yes. Source

Where to start

Clues from write-ups and forum threads, not a diagnosis. Low confidence means one thread or one repair; high means several write-ups agree.

• Power supply filter caps (Medium confidence). One write-up on a power-side repair found a shorted filter capacitor, and also shows swapping the transformer and regulators for a modern SMPS. Source
• Caps by board type (Medium confidence). One shop page shows which capacitor pack fits each 1541 board (Type 1, 2, 3 and 1541-II), including the motor control board, so check your board type first. Source

Tips, tales and maybes

Found in write-ups and forum threads. These are other people's reports, not tested by us. Check part references and values against your own board.

• Story: ?DEVICE NOT PRESENT from a cut jumper trace (Medium confidence). A 1541 returned ?DEVICE NOT PRESENT because a drive select jumper trace had been cut, setting the address to 9. Resoldering fixed it. The same job replaced large smoothing caps with 4700uF 16V (C16) and 6800uF 25V (C17) and warns silkscreen polarity is not always trustworthy. Source
• Tip: Blinking error LED at power-up (Low confidence). A repair guide says an error LED blinking at start points to the power supply side and suggests checking the supply voltage and parts CR3, VR2, VR1 and CR1. It says little about capacitor values. Source
• Story: Burned head coils cannot be recapped away (Low confidence). A batch repair of Commodore drives found two of six 1541s and two Mitsumi drives had burned read/write head coils, which the author says are impractical to rewind. Four 1541-II drives only needed motor and alignment adjustment. Source
• Tip: Recheck speed after a new belt (Low confidence). A pair of 1541 repairs reports a rusted power switch stopping a drive spinning and a hardened belt slipping, and notes a new belt often shifts timing so motor speed and head alignment should be rechecked afterwards. Source

Before you start

• Boards changed during production. Check your board number against the guides before you order parts.
• A mains power supply can hold a dangerous charge. If you are not trained to work on one, have a professional do it.

Manuals and technical documents

Service manuals, schematics and datasheets for this machine, kept in our own library. Check your own board and part numbers against them.

• Service Manual, Model 1540-1541 Disk Drive, Preliminary, April, 1986, PN 314002-01 (Service manual)

All 1 documents for Commodore 1541 and 1541-II drive in the library

Guides we used

This page and the interactive bench are built from these. They have the photos and the full detail, so please read them and support their authors.

• 1541 Capacitors (Kit page) by Retroleum. Has a capacitor list. Shows which capacitor pack fits each 1541 board type (Type 1, 2, 3, 1541-II) including the motor control board; a shop page, not a how-to
• Service Manual Model 1540/1541 Disk Drive (Commodore PN 314002-01, Nov 1985) (Manual) by Commodore (scan on archive.org). Has a capacitor list. Official parts list incl. electrolytic and tantalum caps in the ALPS drive assembly section
• 1541-II repair - Jan Beta (Video) by Jan Beta (via Commodore News). News item with embedded video: drive cleaned, lubricated and electrolytic caps replaced. The YouTube video itself was not opened
• Doktor64 - 1541 Floppy Power Connector Repair & SMPS Mod (Write-up) by ][avok (The Oasis BBS) featuring Doktor64. Power-side repair where a shorted filter capacitor was found; also shows swapping the transformer/LDOs for a modern SMPS

1541 main board 1540001-01 and -03 (early)

Eight capacitors. The two big filter caps (6800 uF and 10000 uF) are the ones that tend to leak.

1541 main board 1540048-01 (later)

Eight capacitors, a slightly different set from the early board.

1541 motor control board (Alps drive)

Three matching 10 uF parts. Check which maker made your drive mechanism before you order.

1541 motor control board (Newtronics, early, 7 caps)

Seven capacitors on the early Newtronics motor board.

1541 motor control board (Newtronics, later, 4 caps)

Four capacitors on the later Newtronics motor board.

1541-II main board 340503

Only three capacitors. Console5 notes that some boards have 50 V parts here, but 25 V is fine.

Shopping list

33 capacitors in all, grouped by value. Buy a few spares.

• 7 x 10 µF, 35 V (check your board): Amazon · eBay
• 4 x 1 µF, 25 V (check your board): Amazon · eBay
• 4 x 47 µF, 16 V (check your board): Amazon · eBay
• 3 x 0.47 µF, 35 V (check your board): Amazon · eBay
• 3 x 10 µF, 25 V (check your board): Amazon · eBay
• 2 x 4.7 µF, 35 V (check your board): Amazon · eBay
• 2 x 100 µF, 16 V (check your board): Amazon · eBay
• 2 x 6800 µF, 25 V (check your board): Amazon · eBay
• 1 x 1 µF, 35 V (check your board): Amazon · eBay
• 1 x 2.2 µF, 35 V (check your board): Amazon · eBay
• 1 x 220 µF, 25 V (check your board): Amazon · eBay
• 1 x 220 µF, 10 V (check your board): Amazon · eBay
• 1 x 4700 µF, 16 V (check your board): Amazon · eBay
• 1 x 10000 µF, 16 V (check your board): Amazon · eBay

Console5 capacitor kits for this machine

Console5 sells ready-made capacitor kits. Kits come in different versions, so match the board number in the kit name to yours and check the listing before you buy.

• Commodore 1540 1541 Floppy Drive Cap Kit

Skip the sourcing

• Ready-made kit: Amazon · eBay
• Already recapped: Amazon · eBay

While you are in there

• Need the machine itself?: Amazon · eBay
• A box of spare capacitors: Amazon · eBay

Affiliate links. As an Amazon Associate I earn from qualifying purchases. These links only search by name. Disclosure

Step by step

1. Photograph both sides of the board before you touch anything. Zoom in on every capacitor. The photo is your map when you are three hours in.
2. Unplug it, take out the batteries and let it sit. Old power supplies and CRT parts can hold a charge. If your machine has a tube, leave the tube and its board to a professional.
3. Open it up and keep the screws sorted. A muffin tin or an egg carton works. Different screws go in different holes, and the holes never forgive you.
4. Look for leaks. Clean any sticky residue off with isopropyl alcohol and a soft brush. A leaked capacitor leaves brown crust and can eat copper traces. Look at the traces under it, not only the part itself.
5. Mark the polarity of every capacitor on the photo before it comes off. On an electrolytic, the stripe marks the negative leg. The board usually shows a half-shaded circle or a bar for the same spot.
6. Remove the old capacitors one at a time. Surface mount: add fresh solder to both ends and rock the part off, or use flux and a low-melt alloy. Through-hole: heat one leg at a time and clear the hole with wick or a pump.
7. Clean the pads and check for lifted pads or damaged traces. Clean flux off with isopropyl. A bad pad needs a jumper wire, not hope.
8. Fit and solder the new capacitor, matching polarity. Same capacity, same or higher voltage, and it has to physically fit. Work from the smallest parts up.
9. Clean the flux off and look at every joint. A good joint is shiny and shaped like a tiny volcano. A dull blob or a ball is a cold joint: reflow it.
10. With a multimeter, check for shorts across the power rails before you power it on. Use the continuity or resistance setting. A reading near zero means stop and look for a solder bridge.
11. Power it up and test everything: video, sound, controls, the lot. If something is wrong, check polarity first. It is the most common mistake and the easiest fix.

Tools

• Temperature-controlled soldering station. Steady heat so you do not cook pads. Most recaps are done between 320 and 350 C. Top: Hakko FX-951 · Mid: Hakko FX-888D · Budget: Pinecil
• Good solder. Rosin-core 63/37 flows and looks right. It is cheap and it matters. Kester 44 63/37
• Flux. Flux is what makes old joints let go and new joints flow. MG Chemicals flux pen · Chip Quik flux syringe
• Low-melt alloy (for surface mount). Melts old solder on both ends of a surface mount part at once, so it lifts off cleanly. Chip Quik SMD1
• Desoldering tool. Clears the old solder out of through-hole pads. Top: Hakko FR-301 · Mid: Engineer SS-02 pump · Budget: Solder wick
• Fine tweezers. For holding small surface mount parts exactly where you want them. ESD-safe tweezers
• Board holder. A third hand for the board, so both of yours are free. PanaVise circuit board holder
• Magnification. You cannot fix what you cannot see. Surface mount parts are tiny. Top: Stereo microscope · Mid: Head visor · Budget: Lighted magnifier
• Multimeter. Continuity, shorts and rail voltages. The one test that saves boards. Top: Fluke 117 · Mid: Fluke 101 · Budget: AstroAI
• ESR and capacitor tester. Checks old capacitors and your new ones before they go in. Top: Peak Atlas ESR70 · Budget: LCR-T7
• Isopropyl alcohol (99%) and a brush. For cleaning leaked goo and flux. Use the high-percentage kind. MG Chemicals 99.9% isopropyl
• Brass tip cleaner. A clean tip transfers heat. A dirty one does not. Hakko 599B
• Fume extractor. Pulls the smoke away from your face. Hakko FA-400 · Budget: Small bench fan
• Precision screwdrivers. Most old gear uses a mix of Phillips, Torx and security bits. iFixit Pro Tech Toolkit
• Kapton tape. Heat-proof tape to protect parts that sit close to the one you are changing. Kapton tape

Safety

• Good airflow, or a fume fan. Solder smoke is not for breathing.
• Safety glasses on. Solder spits and clipped legs fly.
• Iron in its stand when you are not holding it. Know where the cord is.
• Touch bare metal first, or use a wrist strap. Static kills old chips.
• No tube, no mains power supply. Leave those to a professional.
• Wash your hands after, especially if you used leaded solder.

Values are shown as published in the guides above, and boards changed during production. Check the board in front of you. A recap involves hot tools and, on some machines, dangerous voltages. You do it at your own risk.

More

• All recap guides
• The interactive Recap Bench
• Fix a dead vintage computer
• Commodore 1541 on the timeline