Best case scenario is that you've shorted something in the audio signal path to ground, although you'd probably have to have done it to both stereo channels to end up with no output at all. Can you measure the impedance between the pins on the output jack ground with a multimeter?

When i did recapping my MT-32, i damaged at least 5 traces. Not directly traces, but the inner rings where the capacitor legs are supposed to be soldered. I just left cap legs a little bit longer from the lower side of motherboard, and i bent the cap leg and solder them on to the end of traces. Try to look under magnifier or microscope every trace where You changed the caps, maybe somewhere the trace doesn't have continuity with the cap leg.

Could be any number things, a short, broken continuity (bad solder joint, damaged pad/trace), etc.

First thing I would do is use a multimeter to test for both continuity and shorts, specifically testing all replaced components and any other areas that might have been repaired.

I going to try out your suggestions in a few days when I have time to take apart the MT-32 again.

I noticed there were small copper lugs in some of the soldering holes that would easily come out during desoldering of the old capacitors, but I think I got most of them back in place more or less. Those holes were a lot harder to solder without getting cold solder joints though.

Some solder joints took a lot of heat to desolder because of the wide copper traces on the PCB that absorbed a lot of heat. Perhaps some sensitive component got overheated during the process?

There seems to be more problems with the MT-32 than just the audio jacks being silent. The instruments play in the front panel when I start a MIDI-file in Windows, but not when I try to start a game in DosBox. DosBox also crashes when I try to start Monkey Island 2 with Roland music, which means there must be som kind of cross communication that fails. Could this give any hints to which capacitor or other component that is faulty?

Paddan1000 wrote on 2025-03-22, 22:11:

I just replaced all the capacitors in my Roland MT-32. I replaced the caps with Nichicon FW series, except for the four bi-polar caps that were Nichicon MUSE BP. The capacitance is correct for all the capacitors and they are oriented in the correct way. I just used capacitors with a slightly higher voltage rating, but they all fit dimensionally.

Now when I turn on the MT-32 and start a MIDI file the front panel lights up and I can see the instruments playing, but I get no sound from any of the audio out jacks. There isn't even any static, even at the volume turned to 100. They are both completely silent.

What could be the cause of this problem? Is it a short at one of my soldering joints, a loose cable or did I damage a chip?

Curious to know why you replaced the capacitors? The device was manufactured well before the capacitor plague.

zuldan wrote on 2025-03-23, 10:37:

Paddan1000 wrote on 2025-03-22, 22:11:

I just replaced all the capacitors in my Roland MT-32. I replaced the caps with Nichicon FW series, except for the four bi-polar caps that were Nichicon MUSE BP. The capacitance is correct for all the capacitors and they are oriented in the correct way. I just used capacitors with a slightly higher voltage rating, but they all fit dimensionally.

Now when I turn on the MT-32 and start a MIDI file the front panel lights up and I can see the instruments playing, but I get no sound from any of the audio out jacks. There isn't even any static, even at the volume turned to 100. They are both completely silent.

What could be the cause of this problem? Is it a short at one of my soldering joints, a loose cable or did I damage a chip?

Curious to know why you replaced the capacitors? The device was manufactured well before the capacitor plague.

I did it mostly for fun, since I have a bad habit of trying to fix things that are not broken. But I also had a problem where some games didn't sound right in DosBox and ScummVM and was hoping that a recap would fix it. Especcially Monkey Island 2 sounded wrong, with the wrong instruments.

But now I have managed to fix the MT-32. I tested every solder joint that I made yesterday and found 3 that didn't make contact. It was the 3 caps in the top left corner, 2 bipolar ones and one 22 uF polar cap. No matter how much I tried to resolder them it wouldn't work, so I instead created some ugly solder bridges to the adjacent solder point.

Too bad it didn't fix the instrument issue with Monkey Island 2, so I guess it is a compatibility issue with something else. The also are no other improvements in the sound.

Only one weird issue remains. The MT-32 will only give sound output from one of the audio out jacks at a time. If both are connected, only the right one works but if only the left one is connected it will also give sound output which stops immediately if the right one is re-connected. Also, both jacks can give stereo output on their own if connected to a stereo plug. I don't think this issue was present before the re-cap.

The issue with the audio jacks has now been fixed too. It was the lower left bipolar capacitor that had a slipping solder joint, which made contact when I first tested it with a multimeter, but not with the PCB installed in the MT-32 case. The sound would come back if I pressed on the capacitor gently. After resoldering the solder joint both audio jacks work fine.

Here is a picture of the MT-32 PCB with new shiny golden and green capacitors. Apart from looks the MT-32 sounds exactly as before. I have compared old and new recordings done before and after the capacitor change and there is no change in the sound whatsoever. The old capacitors also still tested good.

"I noticed there were small copper lugs in some of the soldering holes that would easily come out during desoldering of the old capacitors, but I think I got most of them back in place more or less. Those holes were a lot harder to solder without getting cold solder joints though."

That is what i wrote You in my first message. I did the same thing while recapp my MT-32 😀 Few copper lugs were "destroyed" by the heat of solder tip, and i just left cap legs a little bit longer, bend them in direction of traces end, and solder the legs onto this end. Everything work perfect after that.... Also changed 7805 inside MT-32, and the caps in PSU.... This should be fine for next 40 Years 😀
Good job with those Nichicon golden babies 😀

I've totally recapped my MT-32 too two years ago, and i must say all of the capacitors excepts two 1000uF in the power filter near 7805 were good. These two was about 60-70% of capacitance.
But, anyway, i've changed them all.

Check for shorts after DAC and demuxer, analog audio circuit is not that big.
EDIT: ah, the problem was solved already. Good.

Paddan1000 wrote on 2025-03-23, 13:11:

I did it mostly for fun, since I have a bad habit of trying to fix things that are not broken. But I also had a problem where so […]
Show full quote

zuldan wrote on 2025-03-23, 10:37:

Paddan1000 wrote on 2025-03-22, 22:11:

I just replaced all the capacitors in my Roland MT-32. I replaced the caps with Nichicon FW series, except for the four bi-polar caps that were Nichicon MUSE BP. The capacitance is correct for all the capacitors and they are oriented in the correct way. I just used capacitors with a slightly higher voltage rating, but they all fit dimensionally.

Now when I turn on the MT-32 and start a MIDI file the front panel lights up and I can see the instruments playing, but I get no sound from any of the audio out jacks. There isn't even any static, even at the volume turned to 100. They are both completely silent.

What could be the cause of this problem? Is it a short at one of my soldering joints, a loose cable or did I damage a chip?

Curious to know why you replaced the capacitors? The device was manufactured well before the capacitor plague.

I did it mostly for fun, since I have a bad habit of trying to fix things that are not broken. But I also had a problem where some games didn't sound right in DosBox and ScummVM and was hoping that a recap would fix it. Especcially Monkey Island 2 sounded wrong, with the wrong instruments.

But now I have managed to fix the MT-32. I tested every solder joint that I made yesterday and found 3 that didn't make contact. It was the 3 caps in the top left corner, 2 bipolar ones and one 22 uF polar cap. No matter how much I tried to resolder them it wouldn't work, so I instead created some ugly solder bridges to the adjacent solder point.

Too bad it didn't fix the instrument issue with Monkey Island 2, so I guess it is a compatibility issue with something else. The also are no other improvements in the sound.

Only one weird issue remains. The MT-32 will only give sound output from one of the audio out jacks at a time. If both are connected, only the right one works but if only the left one is connected it will also give sound output which stops immediately if the right one is re-connected. Also, both jacks can give stereo output on their own if connected to a stereo plug. I don't think this issue was present before the re-cap.

The next time there is a heated discussion about re-capping and someone says that we should replace all caps that are more than 10 years old (I'm exaggerating), I need to remember to refer to this post. 😅

Those caps are, at best, 35 years old... and yet replacing them yielded no perceptible improvement in what was a fairly expensive piece of audio equipment back in the day. Good caps really can last a very very very long time. 🙂

Ozzuneoj wrote on 2025-03-25, 08:00:

Paddan1000 wrote on 2025-03-23, 13:11:

I did it mostly for fun, since I have a bad habit of trying to fix things that are not broken. But I also had a problem where so […]
Show full quote

zuldan wrote on 2025-03-23, 10:37:

Curious to know why you replaced the capacitors? The device was manufactured well before the capacitor plague.

I did it mostly for fun, since I have a bad habit of trying to fix things that are not broken. But I also had a problem where some games didn't sound right in DosBox and ScummVM and was hoping that a recap would fix it. Especcially Monkey Island 2 sounded wrong, with the wrong instruments.

But now I have managed to fix the MT-32. I tested every solder joint that I made yesterday and found 3 that didn't make contact. It was the 3 caps in the top left corner, 2 bipolar ones and one 22 uF polar cap. No matter how much I tried to resolder them it wouldn't work, so I instead created some ugly solder bridges to the adjacent solder point.

Too bad it didn't fix the instrument issue with Monkey Island 2, so I guess it is a compatibility issue with something else. The also are no other improvements in the sound.

Only one weird issue remains. The MT-32 will only give sound output from one of the audio out jacks at a time. If both are connected, only the right one works but if only the left one is connected it will also give sound output which stops immediately if the right one is re-connected. Also, both jacks can give stereo output on their own if connected to a stereo plug. I don't think this issue was present before the re-cap.

The next time there is a heated discussion about re-capping and someone says that we should replace all caps that are more than 10 years old (I'm exaggerating), I need to remember to refer to this post. 😅

Those caps are, at best, 35 years old... and yet replacing them yielded no perceptible improvement in what was a fairly expensive piece of audio equipment back in the day. Good caps really can last a very very very long time. 🙂

not only did it not accomplish anything, but also did PCB damage

This thread does serve as a good warning against doing blind re-capping of boards. Any sort of hardware repair carries a non-zero risk of causing physical damage, as the OP discovered.

More important is knowing how to diagnose issues. OP reported game-specific issues (e.g. Monkey Island 2 instruments sounding incorrect). Game-specific issues are more likely to be software or firmware incompatibilities, not something like bad caps.

Further if a hardware issue is suspected then knowing how to isolate and diagnose the fault is important. For example, I have an SC-55 that his having MIDI input issues. I would start by diagnosing the MIDI input circuitry. Doing something like re-capping the audio circuit would be a waste of time.

I don't agree with theory: "not only did it not accomplish anything, but also did PCB damage"!!! No one can make me believe that 35 Years old caps are better than modern one!

butjer1010 wrote on 2025-03-25, 14:08:

No one can make me believe that 35 Years old caps are better than modern one!

It entirely depends on the capacitors, rated specs, and job they are performing. If the original caps are within spec and performing their function, then replacing them is pointless.

There are cases where it might be worth replacing caps if poor quality ones have been used (e.g. capacitor plague era hardware), or in cases where there were hardware design flaws due to improperly spec'd capacitors. But those cases are going to be more specific than just doing blind re-caps on any old hardware.

It's not worth the risk of damaging old hardware that isn't being made any more.

Ozzuneoj wrote on 2025-03-25, 08:00:

Those caps are, at best, 35 years old... and yet replacing them yielded no perceptible improvement in what was a fairly expensive piece of audio equipment back in the day. Good caps really can last a very very very long time. 🙂

According to Arrhenius’ Law, the lifetime of an electrolytic capacitor doubles with every 10 degree C reduction in operating temperature.
So, for a high quality capacitor that was designed to last for thousands of hours when running @ 105C, you are (potentially) looking at hundreds of years when running in ideal conditions, at close to room temperature. Of course, there are other factors at play here, but... yeah, we should not expect capacitors to fail after 10 or even 20 years of normal use.

Why do we expect them to fail? Because of the widespread fear that the capacitor plague instilled in us, retro enthusiasts. 😀 Let's face it, we deal with a lot of old hardware that was directly affected by that event, so, as a community, we somehow started to assume that capacitors just have a very limited lifespan, when that's far from being true.

Having said that, capacitor replacement is a very easy & safe thing to do, if you have the experience (and proper tools). The first board I recapped 20 years ago was left in - what would've been - an almost unusable state (it was a scrap board that I practiced on), and the whole job took more than 4 hours, for sure. Nowadays, recapping a motherboard with 20 - 30 capacitors takes me anywhere between 15 and 30 minutes, with absolutely no risk to the board itself.

bloodem wrote on 2025-03-25, 14:32:

According to Arrhenius’ Law, the lifetime of an electrolytic capacitor doubles with every 10 degree C reduction in operating tem […]
Show full quote

Ozzuneoj wrote on 2025-03-25, 08:00:

Those caps are, at best, 35 years old... and yet replacing them yielded no perceptible improvement in what was a fairly expensive piece of audio equipment back in the day. Good caps really can last a very very very long time. 🙂

According to Arrhenius’ Law, the lifetime of an electrolytic capacitor doubles with every 10 degree C reduction in operating temperature.
So, for a high quality capacitor that was designed to last for thousands of hours when running @ 105C, you are (potentially) looking at hundreds of years when running in ideal conditions, at close to room temperature. Of course, there are other factors at play here, but... yeah, we should not expect capacitors to fail after 10 or even 20 years of normal use.

Why do we expect them to fail? Because of the widespread fear that the capacitor plague instilled in us, retro enthusiasts. 😀 Let's face it, we deal with a lot of old hardware that was directly affected by that event, so, as a community, we somehow started to assume that capacitors just have a very limited lifespan, when that's far from being true.

Having said that, capacitor replacement is a very easy & safe thing to do, if you have the experience (and proper tools). The first board I recapped 20 years ago was left in - what would've been - an almost unusable state (it was a scrap board that I practiced on), and the whole job took more than 4 hours, for sure. Nowadays, recapping a motherboard with 20 - 30 capacitors takes me anywhere between 15 and 30 minutes, with absolutely no risk to the board itself.

I agree with most of this.

The issue is that most people just starting now (or recently) aren't going to be getting 20 years of experience on junk boards. Most of the stuff you worked on 20 years ago was probably not using lead-free solder. Now, anything that old is getting rare and is a lot more valuable. And more modern boards that are cheap\worthless are using far fewer through-hole components and are using lead-free solder which is much harder to work with.

I am far better at replacing caps than I was 20 years ago too, but I don't do it professionally and have only in the last 5 years gotten to the point of not feeling like I'm going to destroy everything I work on... and even then, things can still get damaged easily if the wrong technique is used or if I simply make a mistake.

Leaving caps alone unless they are a known source of problems is going to be the best decision for most retro enthusiasts for probably at least a couple more decades. By all means, practice on things and learn how to repair them, but don't dive into full recaps of stuff that is desirable, rare and known for having exceptional build quality... especially Japanese gear. The caps and even batteries in most Japanese-made electronics seem to last forever. 😅

For practising solder and de-solder techniques, I'd recommend using practice soldering kits. There are through-hole kits available and you can solder and desolder them as much as you want.

Practising on blank prototype boards is another option.

For lead-free de-soldering, I would try to get scrap boards especially hardware that is non-recoverable. Can also be a good way to salvage spare components.

Shponglefan wrote on 2025-03-25, 17:51:

For practising solder and de-solder techniques, I'd recommend using practice soldering kits. There are through-hole kits available and you can solder and desolder them as much as you want.

As a starting point, they are good. But they will not be comparable to motherboards which have large ground planes that quickly absorb heat. Sooner or later... scrap boards FTW! 😀

Ozzuneoj wrote on 2025-03-25, 16:15:

I agree with most of this. […]
Show full quote

I agree with most of this.

The issue is that most people just starting now (or recently) aren't going to be getting 20 years of experience on junk boards. Most of the stuff you worked on 20 years ago was probably not using lead-free solder. Now, anything that old is getting rare and is a lot more valuable. And more modern boards that are cheap\worthless are using far fewer through-hole components and are using lead-free solder which is much harder to work with.

I am far better at replacing caps than I was 20 years ago too, but I don't do it professionally and have only in the last 5 years gotten to the point of not feeling like I'm going to destroy everything I work on... and even then, things can still get damaged easily if the wrong technique is used or if I simply make a mistake.

Leaving caps alone unless they are a known source of problems is going to be the best decision for most retro enthusiasts for probably at least a couple more decades. By all means, practice on things and learn how to repair them, but don't dive into full recaps of stuff that is desirable, rare and known for having exceptional build quality... especially Japanese gear. The caps and even batteries in most Japanese-made electronics seem to last forever. 😅

For sure! I agree that replacing caps "just because" is not recommended unless you have a good reason to do so (even though even I, myself, did it quite a bit more than once 😁 ). One thing I always do, though, when replacing caps is test them - and, funnily enough, I've had situations where the 20+ year old caps I was replacing were testing better than the ones I was replacing them with 😀

bloodem wrote on 2025-03-25, 19:23:

For sure! I agree that replacing caps "just because" is not recommended unless you have a good reason to do so (even though even I, myself, did it quite a bit more than once 😁 ). One thing I always do, though, when replacing caps is test them - and, funnily enough, I've had situations where the 20+ year old caps I was replacing were testing better than the ones I was replacing them with 😀

Funny you mention that! I had a similar experience which I documented and created a whole thread about it:

Testing old caps with an ESR meter.

Yikes... that was seven years ago? Blegh.