Well, you haven't given much details of your setup and what you've tried so far, but as a general rule, those old SB:s seldom break. I'd begin with trying other speakers/headphones, just to rule that out, and then start troubleshooting on the software side. Check the balance settings. If you use W98, you could check if there's any difference between the Windows and the DOS drivers.

I tested with Diagnose and Windows 95 with headphones. Other cards work fine with this setup.

It's weird as only one channel plays. Could it be a problem with some chip on the card?

Mixer settings. If not that, could be a broken solder joint.

Maybe short on line out connector will prevent the amplifier from getting input signal so therefore amplifier output is also silent.
Have you checked it's not the connector that is broken?
Can you post (good, clear, high-res) pictures of both sides of the card so we could take a look?

Sure. What bothers me that both line out and speaker out do the same.

firage wrote:

Mixer settings. If not that, could be a broken solder joint.

If mixer settings are okay, I'd begin back tracing the analog signal path. You might have to beg/borrow/steal a scope to troubleshoot this properly.

gdjacobs wrote:

firage wrote:

Mixer settings. If not that, could be a broken solder joint.

If mixer settings are okay, I'd begin back tracing the analog signal path. You might have to beg/borrow/steal a scope to troubleshoot this properly.

Never checked the mixer settings but I'd guess Diagnose sound check does it what is says. Testing left/right channel.

I don't have any proper hardware to do advanced troubleshooting. In the end it's probably not worth the effort.

In what type of PC are you testing this?

This may sound silly, but try testing the sound card in a different PC and see what the results are.

firage wrote:

Mixer settings. If not that, could be a broken solder joint.

That's something I would try. If you have a solder iron, heat up every solder joint.

I did this with a non-working GUS PnP and it came back to life 😀

jesolo wrote:

In what type of PC are you testing this?

This may sound silly, but try testing the sound card in a different PC and see what the results are.

It's some generic Pentium 133. I do all my tests on this machine. But will try with another.

PhilsComputerLab wrote:

firage wrote:

Mixer settings. If not that, could be a broken solder joint.

That's something I would try. If you have a solder iron, heat up every solder joint.

I did this with a non-working GUS PnP and it came back to life 😀

Nice idea. I have a solder iron 😉

I have a CT3600 where both channels are really really low in terms of sound volume, and the sound is also distorted. I have to turn the volume controls all the way up to be able to faintly hear anything. Have you checked if the silent channel you have isn't having this same problem? If it is, then I hope you find the solution and that it applies to my card as well 😁

devius wrote:

I have a CT3600 where both channels are really really low in terms of sound volume, and the sound is also distorted.

Very typical when the TO92 5v regulators die, all the op-amps are fed from them.

James-F wrote:

Very typical when the TO92 5v regulators die, all the op-amps are fed from them.

If that's the issue then it's super easy to diagnose and fix 😳 I hope you're right!

Also, there are only two main outputs (L/R) from the mixer chip, you can trace them back from the line-out to the mixer chip.
These outputs are split to the Line-Out and Power-amp chip inputs through some components.

Play a sinewave using MPXPlay (dos) or Windows and Scope the mixer outputs.
If it's not a pure sine-wave the problem is before the mixer chip.

Is the FM/OPL3 working correctly?

No, nothing works correctly in my case, which would seem to indicate a problem after the mixer right?

I don't have a scope, but I can use powered speakers to test the audio path by ear.

James-F wrote:

devius wrote:

I have a CT3600 where both channels are really really low in terms of sound volume, and the sound is also distorted.

Very typical when the TO92 5v regulators die, all the op-amps are fed from them.

Makes sense. If the regulators are outputting low, the audio waveform is going to flat top.

devius wrote:

No, nothing works correctly in my case, which would seem to indicate a problem after the mixer right?

No necessarily.
The YAC512 which is the YMF262 DAC is also fed from the 5V and -5V regulators.
Check the 5V and -5V regulators, they are fed from the 12V and -12V rails.
Be careful not to short the regulators legs when probing.

James-F wrote:

The YAC512 which is the YMF262 DAC is also fed from the 5V and -5V regulators.

YAC512 uses only +5V, not -5V, and I think CT3600 does not even have YMF262/YAC512 chips.

But sure, op-amps usually use +5V and -5V from onboard regulators so that might be the cause.

Correct. It has the CT1978 CQM / bus chip.