Which GUS exactly ?

Since you mention hearing a faint audio signal, I'm leaning towards either bad caps, bad voltage line (+12v) or bad output stage/amplifier on the GUS or failed voltage regulator on the GUS itself.

And all of a sudden it's now working. After many many reboots -- 100%. Why??

Failing components can result in intermittent behaviors where sometimes things appear to work, but then they stop working.

Since you reported hearing faint sounds previously I'd wager there is something in the audio output circuit that might be failing (e.g. after the DAC).

It might be something as simple as corrosion on the audio jack.

Shponglefan wrote on 2023-12-28, 18:52:

Failing components can result in intermittent behaviors where sometimes things appear to work, but then they stop working.

Since you reported hearing faint sounds previously I'd wager there is something in the audio output circuit that might be failing (e.g. after the DAC).

It might be something as simple as corrosion on the audio jack.

Agreed,
or a cracked solder joint.

Tht sounds like a mechanical issue indeed. My GUS has pretty bad output connectors, the plugs barely stay in and sometimes there's poor contact too. Perhaps yours is even worse and could use a connector replacement or at least a cleanup if possible.

My Gus needs an audio jack replacement as well. Any recommendations on parts? I can sacrifice one of those old OEM SB live cards I have lying around I guess. Seems like a fitting punishment. 😁

On my own GUS Max that had audio out jack issues, I just replaced it using the mic in jack. I figure I'm never likely to use a microphone with that card, so...

If all the chips (GF1 etc.) on the GUS are socketed then pressing those down may help.

Joakim wrote on 2023-12-28, 22:05:

My Gus needs an audio jack replacement as well. Any recommendations on parts? I can sacrifice one of those old OEM SB live cards I have lying around I guess. Seems like a fitting punishment. 😁

I recently replaced the broken jacks of a GUS PnP with CUI Devices SJ1-3533NG.

My original GUS developed a bad headphone jack, exactly like you described. I ended up cutting of the end of a headphone extension cable and soldering the wires to the back of the card 😁

Shortly after my orig post, here, the card started outputting normally. Used it for hours just fine. The next day, today, it's back to where it was.

So, I pulled the GUS out and I don't see any bulging or leaking caps. The feel of the 1/8" jack is looser / wobblier a bit on the upper (output) jacks than the never-used input jacks. I get no normal output through either output jack attached to my Audioengine A5 speakers. I can hear FAINT audio when volume is at max on the speakers out of the Line-out (unamplified) jack, but I don't THINK that I can hear the same out of the top (amplified) output. I also see no heat flaring around the voltage regulators.

Bad caps would show some kind of sign likely, right? Bulge or leak? I'd like to fix this and am wondering what my best approach is likely to be. Thanks.

bp

blakespot wrote on 2023-12-30, 20:06:

Shortly after my orig post, here, the card started outputting normally. Used it for hours just fine. The next day, today, it's back to where it was.

So, I pulled the GUS out and I don't see any bulging or leaking caps. The feel of the 1/8" jack is looser / wobblier a bit on the upper (output) jacks than the never-used input jacks. I get no normal output through either output jack attached to my Audioengine A5 speakers. I can hear FAINT audio when volume is at max on the speakers out of the Line-out (unamplified) jack, but I don't THINK that I can hear the same out of the top (amplified) output. I also see no heat flaring around the voltage regulators.

Bad caps would show some kind of sign likely, right? Bulge or leak? I'd like to fix this and am wondering what my best approach is likely to be. Thanks.

Maybe clean those edge connector (ISA) pads, the look very dirty. Maybe the card wasn't getting the required power at some point.

Can you post a close up photo of the solderpads of both 317T regulators ?

By no heat flaring, do you mean no discoloration, like no slight browning around hot components ? which is good.
look for any ring like patterns in the solder, those can form due to thermal variations and resoldering those points, adding a little solder, fixes that, if any exist.

pan069 wrote on 2023-12-30, 20:16:

Maybe clean those edge connector (ISA) pads, the look very dirty. Maybe the card wasn't getting the required power at some point.

That's mainly reflection angle of the light above -- it's scored but it looks quite clean, still - I did give the connectors a clean just now. Will try it out.

bp

Hold on --- what is RN2? I just noticed this...

bp

UPDATE: Looking back on build photos from 2014, I see that haze of whatever it is is there, just over RN2, so probably is not new. I can't confirm it was among the legs there, but the part on the red board was there back then (and it's been working fine until just the other day).

What I did to this PC recently that had me using it (it's been a while) is upgrading boot disk to CF card from mobo IDE controller and I did have to remove the GUS to get to the BIOS battery that was dead and I replaced. But, after putting it back together, GUS worked fine until the next day, so...

weedeewee wrote on 2023-12-30, 20:43:

Can you post a close up photo of the solderpads of both 317T regulators ?

By no heat flaring, do you mean no discoloration, like no slight browning around hot components ? which is good.
look for any ring like patterns in the solder, those can form due to thermal variations and resoldering those points, adding a little solder, fixes that, if any exist.

Here's the shot.

bp

blakespot wrote on 2023-12-31, 00:15:

weedeewee wrote on 2023-12-30, 20:43:

Can you post a close up photo of the solderpads of both 317T regulators ?

By no heat flaring, do you mean no discoloration, like no slight browning around hot components ? which is good.
look for any ring like patterns in the solder, those can form due to thermal variations and resoldering those points, adding a little solder, fixes that, if any exist.

Here's the shot.

bp

What's happening on the trace near R33?

Edit: Looking at my own card (same version as yours) it's a via but mine look like a properly tinned one (i.e. silvery in color).

Edit: What does the rear of your card look like? Can you post a photo?

It is worth reseating all the jumpers in 2x4 conf, they pass analog audio and are there for the 16bit play/record addon board that basically nobody has. JP4 and JP5 in particular as they carry GF1 output and total mix outputs. Other two are line and microphone inputs and not so improntant.

The card looks good on photos. The vias near R33 on one photo look like corroded through but on another they do look right, must have been a reflection issue during photo.

blakespot wrote on 2023-12-30, 20:06:

I'd like to fix this and am wondering what my best approach is likely to be. Thanks.

What sort of equipment do you have? Do you have a multimeter? Oscilloscope?

Generally my initial diagnostics approach would be:

1) Physical inspection for damage (corrosion, damaged components, broken solder joints)
2) Checking for shorts and continuity
3) Checking voltages and resistances

Since you mention being able to hear faint audio, that's a good sign that the sound generation portion of the card including the main chip is probably okay. My first area to focus on would be the analog portion of the audio circuit. I'd probably start with components like the voltage regulators, DAC, amplifier chips, caps, etc.