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Thread: Weird PSU/sound card issues with 486

  1. #1

    Default Weird PSU/sound card issues with 486

    Hi everyone, I recently attempted to fire up my trusty DOS 486. Tried to turn it on, nothing happened. It seemed that no power was getting to the PSU, the PSU fan wasn't turning, etc. I took it apart, cleaned it, and after a few tries the PSU started back up. Put everything back together, and the PC turned on just fine, no issues.

    I then tried to play a game (Doom) and realised that no sound was coming out. Upon further inspection, I could barely hear the sound FX when turning the speaker all the way up, and no music whatsoever. Same with every other game I played. Occasionally a super loud high-pitched noise would come out of the speakers. This led me to believe that my SB AWE 32 had died. I pulled it out to have a look, cleaned it, put it back in and then... my video card stopped working.

    Cleaned the video card, plugged it back in... nothing. Eventually I plugged it into a different port and I got video back. But the sound card still had problems.

    I ended up getting a new (to me) sound card (ESS ES1868F). I got it today in the mail, looks to be in good shape. Plugged it in, installed the drivers and... the sound problem remains. I get a little bit of FX after turning the volume all the way up, and no music.

    Anyone has any idea what I could try next? Was all this caused by my PSU? Is my motherboard bad? Please help!

  2. #2
    Join Date
    Feb 2014
    Location
    South Bend, IN
    Posts
    102

    Default

    Hmm... first question is if the speakers are ok. Then I wonder if you had a power surge or other event that took out the PSU and/or parts of the motherboard. I have had surges selectively take out ports on a board before.

  3. #3

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    I tried the speakers with other devices and they work ok.
    Its confusing that the PSU kinda died and then came back to life. But the only other experience I ever had with a PSU malfunctioning involved smoke and flames... so I don't have lots of experience here.
    Also everything else seems to work fine now. Except for the sound...

  4. #4

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    Check all voltage rails on the PSU. It may not deliver a voltage like -5V, which the sound card may use.

  5. #5

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    Quote Originally Posted by Timo W. View Post
    Check all voltage rails on the PSU. It may not deliver a voltage like -5V, which the sound card may use.
    Ok, I'll do that, thanks. That being said, I've used that soundcard and PSU for years now without any issue, so it must have been supplying power to the sound card just fine. Is it possible for the PSU to be only partially damaged, and therefore not supplying power to the soundcard anymore?

  6. #6

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    Sure, it's possible for a PSU to fail in a way that only affects one voltage rail.

  7. #7

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    Quote Originally Posted by Timo W. View Post
    Sure, it's possible for a PSU to fail in a way that only affects one voltage rail.
    Ok, so I finally had the time to give this a go. Here are the results:
    (I wrote them down using the colours for each pin)

    Red: 5.1 V
    Red: 5.1 V
    Red: 5.1 V
    White: -4.97 V
    Black
    Black

    Black
    Black
    Blue: -11.23 V
    Yellow: 12.05 V
    Red: 5.1 V
    Orange: 5.1 V

    I don't know much about this, but it looks like the blue wire isnt getting as much voltage as it should. Would this cause the problem? What do I do next?

  8. #8

    Default

    -11.23 V on the -12V rail should be fine.

    However, the easiest way to rule out the PSU as the culprit would be to simply try with a different PSU. If that won't change things, the mainboard would be next.

    Before doing any hardware changes, did you try booting into a clean DOS environment e.g. by using a boot disk? Could be just a software problem, at least when it comes to the sound issues you have. Also, resetting the BIOS values and ESCD can do wonders sometimes.

  9. #9

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    My BIOS battery has been broken for years, so it resets every time I turn it on! And this PC is booted directly into DOS 99% of the time (I've got Win98 in it but hardly ever use it. In any case, I checked my boot files, and had to change them when I installed the new drivers for the new sound card. So I'm not sure on what else to do...

    I bought a new PSU but I'm not sure if it'll work (I dont know much about the subject). Its this: https://www.ebay.com.au/itm/SPEED-AT...53.m2749.l2649

    Since it has a different connector, I also bought this adapter: https://www.ebay.com.au/itm/20P-ATX-...53.m2749.l2649

    Will this work? I'm not too sure of what I'm doing here, and I don't want to blow my PC up.

    Thanks!

  10. #10

    Default

    Quote Originally Posted by conradspitfire View Post
    Will this work? I'm not too sure of what I'm doing here, and I don't want to blow my PC up.
    Yes, that should work.

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