VOGONS


First post, by Paar

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Hi. I've bought nice looking CT2760. Drivers detect the card fine but whenever I try to play any sound or music, I can hear only buzzing. When I exit a game buzzing stops. Sometimes I can somewhat hear the music in the buzzing (like in the menu in Wolf3D or Duke3D when AWE32 synth is selected). Applies for both Speaker and Line out. Sound effects are just pure buzzing.

Tried to look at the card with magnifying glass but haven't found any significant damage. After installing SB32 CT3620 the sound worked fine so it's definitely a problem with the card. I've tested in in two systems, based around 486 and Pentium II CPUs.

I'd like to ask if there is someone who experienced the same symptoms? There are a lot of caps which could go bad and I could replace them one by one I would rather ask first here. Is it for example possible that the CT1745 mixer chip died? Thanks for any input!

The photo in the link is just some I've found online, it's not the card I have. Looks the same though.

Reply 1 of 10, by kixs

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What drivers are you talking about? How did you configure the card?

You can always just run UNISOUND and than the game setup to select sound card.

If this doesn't work, post hires photos of the front and back of your card.

My Amibay | - Updated on 2022-07-13 | Requests also possible

Reply 2 of 10, by Paar

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I think I tried drivers from this link: http://www.vogonsdrivers.com/getfile.php?file … menustate=45,38

There are several archives inside, not sure which one I've chosen. Run the install program in DOS and let it configure everything. The card gets detected everywhere but produces only buzz. Tried original Win98SE drivers which are included on the CD. The same result.. I can try UNISOUND but I think there is some HW problem on the card.

Will post some picutures tomorrow.

Reply 4 of 10, by RockstarRunner

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I have a Vibra16S which was exhibiting a horrible static/screeching sound. The actual audio was there, but it was buried by the noise.
Turned out it was the amp chip, which should be this one I've highlighted on your card.

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Replaced the chip (easily found on eBay) and the noise was gone, and the audio was as it should be.
Can't say it's the same problem you have, but worth looking in to, if you don't have any better ideas.

Reply 5 of 10, by mkarcher

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Paar wrote on 2022-04-05, 08:28:

Here's pictures. Please note that I've removed one electrolytic cap (C101, middle down) that looked damaged to verify it's ok. Measured good so the problem is elsewhere.

The caps that can kill your sound are the caps in the top right quarter of your card. A quick check you can do to test whether the problem is in the analog part (so most likely the caps) or the digital part of your card: Set the mixer to record "What-U-hear", i.e. the audio output of your card. This enables loopback from the output of the 1745 mixer chip to the input without needing the caps and amplifiers in the top right part. You can then play a MIDI file in Windows and record the output using the Sound Recorder. Play back the recording with a working sound card. If the recording sounds OK, some caps in the top right part are most likely the source of your problem.

Reply 6 of 10, by Paar

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RockstarRunner wrote on 2022-04-05, 12:13:

I have a Vibra16S which was exhibiting a horrible static/screeching sound. The actual audio was there, but it was buried by the noise.
Turned out it was the amp chip, which should be this one I've highlighted on your card.

I have the problem even when listening to the audio through Line Out, bypassing the amplifier. So it probably is not the source of the problem. Probably.

mkarcher wrote on 2022-04-05, 12:21:

The caps that can kill your sound are the caps in the top right quarter of your card. A quick check you can do to test whether the problem is in the analog part (so most likely the caps) or the digital part of your card: Set the mixer to record "What-U-hear", i.e. the audio output of your card. This enables loopback from the output of the 1745 mixer chip to the input without needing the caps and amplifiers in the top right part. You can then play a MIDI file in Windows and record the output using the Sound Recorder. Play back the recording with a working sound card. If the recording sounds OK, some caps in the top right part are most likely the source of your problem.

That's a good idea. Do I get it right that I should record some music with some software in Windows? Any tips for suitable SW compatible with Win9X? EDIT: You mentiones Sound Recorder... I'll try that.

Reply 7 of 10, by mkarcher

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Paar wrote on 2022-04-05, 13:07:
RockstarRunner wrote on 2022-04-05, 12:13:

I have a Vibra16S which was exhibiting a horrible static/screeching sound. The actual audio was there, but it was buried by the noise.
Turned out it was the amp chip, which should be this one I've highlighted on your card.

I have the problem even when listening to the audio through Line Out, bypassing the amplifier. So it probably is not the source of the problem. Probably.

Typically, there are multiple amplifier chips on sound cards. Your test of the line-out jack most likely rules out the power amplifier chip as root for your problem, so it definitely helps narrowing down the issue, but often sound cards also have low-power amplifier chips like the TL074 or the NE5532 between the mixer chip and even line-out. Electrolytic caps are considerably more prone to failure, so amplifier failure is unlikely, but I won't put all my money on the amplifiers being fine.

Reply 8 of 10, by Paar

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I've done some testing today in Windows 98. Unfortunately, I haven't managed to get mixer output on the Line In so I was unable to record anything. Everytime I tried to play something, the player looked fine (device manager didn't show any problems either), but when checking Mixer utility from Creative, there was none activity shown on the visual equalizer. Tried SB32 and equalizer was nicely active. I'm suspecting that the mixer chip could be a culprit.
But not all was a failure. I've connected Dreamblaster X1 to the AWE32 and connected headphone directly to the DB throu headphone jack and heard MIDI music just fine. Tried Line Out and heard only buzzing. That means data goes to the wavetable header properly.

Reply 9 of 10, by mkarcher

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Paar wrote on 2022-04-05, 19:00:

But not all was a failure. I've connected Dreamblaster X1 to the AWE32 and connected headphone directly to the DB throu headphone jack and heard MIDI music just fine. Tried Line Out and heard only buzzing. That means data goes to the wavetable header properly.

OK, so the main problem is clearly on the analog side of the card. The most likely culprits are electrolytic caps, amplifier chips voltage regulators and the mixer chipfor the analog part (ordered by how likely I expect the thing to be the culprit).