Recap guide

Recap the Roland MT-32 and CM-32L

About 20 electrolytics, including bipolars. Several owners measured the original Sanyo caps as mostly in spec, yet LAPC-I owners reported lost or muffled channels cured by replacing every electrolytic.

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

Check first. A recap is not always the answer here, so look at the guides before you order parts.

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.

• MT-32 old (rev 0) (Medium confidence). How to tell: No headphone jack on the rear; serial numbers up to 851,399 per Wikipedia, early LA32 in an 80 pin PGA package. Capacitors: A VOGONS thread says the only cap difference between old and new revisions is one extra bipolar cap on the old boards and fewer caps overall on newer ones; service manuals list 4 or 5 electrolytics but 20 or 21 are fitted. Console5 sells a kit for early units. Capacitor list differs from other revisions: yes. Source
• MT-32 new (rev 1, headphone jack) (Medium confidence). How to tell: Stereo headphone jack on the rear panel and faster Intel P8098 CPU; serials from 851,400 upward on Wikipedia's list. Capacitors: Same VOGONS thread: fewer caps overall than the old revision. One owner found C40 and C41 (470uF 16V input filters) bulged. Originals were Sanyo with KMG bipolars. Capacitor list differs from other revisions: yes. Source
• CM-32L (Low confidence). How to tell: Rack style unit with only a volume knob, MIDI message and power LED; early units resemble the new MT-32 inside. Capacitors: No capacitor information found for the CM-32L. 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.

• Bulged or weak caps (Low confidence). One MT-32 had bulged 470uF/16V caps C40 and C41, and another had two 1000uF PSU filter caps near the 7805 down to roughly 60-70% of their rating. Source
• Muffled or missing channel (LAPC-I) (Low confidence). On an LAPC-I card, right-channel loss and muffled sound were cured by replacing all the electrolytics, according to one thread. Source
• A recap can backfire (Low confidence). In one thread an MT-32 went silent after a recap because of bad joints and lifted pads, with no audible improvement. 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.

• Watch out: Bent capacitor leads shorted an LAPC-I (Medium confidence). An LAPC-I that arrived dead had the long leads of C33 bent so two touched each other and a pin of IC22. Straightening them with pliers brought it back to life. The author says the card needs a rigid protective box for storage, since an anti-static bag or bubble wrap is not enough. Source
• Tip: LAPC-I recap rules from a thread (Medium confidence). A thread on an LAPC-I that cut out or lost a channel says replacing all electrolytics fixed it, using low-ESR radials of the same uF, equal or higher voltage, and not switching capacitor type. Negative leads go to the pads marked with circles, and a damaged 4MHz crystal near C33 was also found. Source
• Story: Distorted mids and lows was a ROM, not caps (Medium confidence). An MT-32 with distorted mid and low frequencies, a clean self-test and capacitors and PCM54HP already replaced was eventually fixed after about four months by replacing IC37, a ROM-type chip, with a programmed substitute. Check logic and ROM before blaming sound-path caps. Source
• Story: Originals still tested good (Low confidence). After a recap with Nichicon FW and MUSE BP bipolar caps that went silent until three cold joints were fixed, the poster said the original caps had still tested good and he heard no improvement. One person's experience, not a rule. 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.

• Roland MT-32 Service Notes First Edition (Service manual)

All 1 documents for Roland MT-32 and CM-32L 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.

• MT-32 Capacitor map and list of caps? (Forum) by CrossBow777 and VOGONS members. Has a capacitor list. Best single source: capacitor map and parts list for Rev 0/1 boards, later corrected, plus an updated spreadsheet of Nichicon equivalents; thread also mentions a Console5 kit and a video
• MT-32 completely silent after capacitor replacement. (Forum) by Paddan1000 and VOGONS members. Cautionary write-up: Nichicon FW/MUSE BP recap, then silence from bad joints and lifted pads; no audible improvement; ESR test results on page 2
• Faulty LAPC-I (Forum) by DonutKing and VOGONS members. LAPC-I symptom fixed by replacing all electrolytics; tips on radial low-ESR parts, polarity marks and the CM32L control ROM v1.02 fix
• MT-32 help with jumper wires (Forum) by VOGONS forum thread. Recapping accident (damaged vias) with ESR measurements showing old caps still near spec; useful counterweight and repair advice

MT-32 main board 79377310, Rev 00 and 01

Twenty-three capacitors. Four are bipolar, so use non-polar parts at C1, C3, C11 and C16.

Shopping list

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

• 6 x 100 µF, 16 V (check your board): Amazon · eBay
• 4 x 10 µF, 16 V (check your board): Amazon · eBay
• 4 x 22 µF, 16 V (check your board): Amazon · eBay
• 4 x 1000 µF, 16 V (check your board): Amazon · eBay
• 2 x 1 µF, 50 V (check your board): Amazon · eBay
• 2 x 470 µF, 16 V (check your board): Amazon · eBay
• 1 x 47 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
• Roland MT-32 on the timeline
• Roland CM-32L on the timeline
• Roland LAPC-I on the timeline