Recap guide

Recap the Commodore Amiga 3000 and 4000

SMD electrolytics leak under the board, the A4000 is a recognised recap target, and kits exist.

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.

• A3000 revisions 6.3 and 9.3 (Low confidence). How to tell: Revision numbers named by a UK recap shop. Capacitors: Shop says it covers all board revisions; no cap list. Capacitor list differs from other revisions: not known. Source
• A4000 desktop rev B (Low confidence). How to tell: Amiga PCB Explorer covers this one board. Capacitors: An AmigaKit pack says quantity, values and type vary with the motherboard model. Capacitor list differs from other revisions: not known. 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.

• Leaking SMD caps (Low confidence). Kit and service sellers describe leaking SMD electrolytics on A4000 boards. One kit page says values vary by board model and does not list them. Source
• Repairing leak damage (Low confidence). The Amiga PCB Explorer is a trace and layout viewer for repairing damage after a leak. The news item covers an A4000 Rev B. 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: A4000 board eaten by battery and caps (Low confidence). A multi-part video series covers an Amiga 4000 motherboard with heavy corrosion from a leaky battery and capacitors. The page only embeds the video, so details are not in text and this is a pointer rather than a documented fix. Source

Before you start

• Boards changed during production. Check your board number against the guides before you order parts.

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.

• A4000 Capacitor Pack for Professional Recapping (Kit page) by AmigaKit. Kit page; says values vary by board model and does not list them
• Amiga 4000D Capacitor Replacement Kit (Kit page) by DragonBox. Recapping service; describes the problem generally
• Amiga PCB Explorer (Write-up) by Christian Euler (via Amiga News). Trace and layout viewer for repairing damage after cap leaks; A4000 Rev B

Power supply (14 parts)

From oldcrap.org's list for the Amiga 3000 (not the 4000), noted from the original parts. Two 3300 uF parts are 10 V and one is 16 V on this list, so check each one before you order.

Second power-supply group (3 parts)

The list gives these three under a separate heading called PSU2, so they may sit on a different part of the supply.

Motherboard (32 parts)

From oldcrap.org's list. Most are 47 uF 16 V and 22 uF 35 V, and seven are 470 uF 16 V.

Shopping list

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

• 20 x 47 µF, 16 V (check your board): Amazon · eBay
• 7 x 22 µF, 35 V (check your board): Amazon · eBay
• 7 x 470 µF, 16 V (check your board): Amazon · eBay
• 3 x 1 µF, 50 V (check your board): Amazon · eBay
• 3 x 220 µF, 25 V (check your board): Amazon · eBay
• 2 x 4.7 µF, 35 V (check your board): Amazon · eBay
• 2 x 470 µF, 200 V (check your board): Amazon · eBay
• 2 x 3300 µF, 10 V (check your board): Amazon · eBay
• 1 x 4.7 µF, 50 V (check your board): Amazon · eBay
• 1 x 100 µF, 16 V (check your board): Amazon · eBay
• 1 x 3300 µF, 16 V (check your board): Amazon · eBay

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 Amiga 3000 on the timeline
• Amiga 4000 on the timeline