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Thread: dying power supply?

  1. #1

    Default dying power supply?

    I have a quantex with a Am486dx4-S 120mhz and im thinking of gutting it and using the case for a retro styling case for my gaming computer, it has a little mhz display on the front. I think it runs on 5v power, but i took my volt meter and hooked it up to the leads for it (it runs on a special connector directly from the power supply,) and it showed up as 3.3v. Confused, I connected the voltmeter to the 5v wires on the molex adapters from the power supply, and it showed up as the same 3.3v. Then i tested the 12V leads, and it showed up as 10v. I think the power supplies they used in them (AGI,) were pretty spotty. This computer had it replaced in '97. So I guess after 11 years, you might see some drop in voltage. But I can't believe the comptuer runs so good on that large of a drop of voltage.

    Also, do you guys think its ok to gut that computer (it actually was a pent 1 75mhz, but i downgraded it to a am486dx4-s cpu,) or should i keep it. It would make a really cool new case mod.
    "I think computer viruses should count as life. I think it says something about human nature that the only form of life we have created so far is purely destructive. We've created life in our own image." - Steven Hawking

  2. #2
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    I doubt the computer would work if the 5VDC was actually at 3.3VDC

    That's WAY outside the tolerance range and almost a 40% drop from ideal.

    A 486 system wouldn't draw that heavily on the +12VDC line and it's below tolerance as well.

    I suspect that your meter is out by around 2V DC
    Legacy Computers and Parts

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  3. #3
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    it actually was a pent 1 75mhz, but i downgraded it to a am486dx4-s cpu,
    The Pentium 75 runs on 3.3V (see http://en.wikipedia.org/wiki/Pentium).
    So it sounds like you have an ATX power supply (see http://www.playtool.com/pages/psurailhistory/rails.html), found the +3.3V line, but have yet to locate the +5V line.

  4. #4

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    Yes, it is atx, but I was taking the voltages from the molex adapters for a hard drive/cd drive.

    I'll have to check that meter with another power supply. It might be bad, but its a 1500 dollar one my dad had from when he worked at waterlift (where they made the legs for the lunar lander.)
    "I think computer viruses should count as life. I think it says something about human nature that the only form of life we have created so far is purely destructive. We've created life in our own image." - Steven Hawking

  5. #5
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    Well, it just seems that, if you added 2V to the readings you got they would be close to ideal.

    Since you say the system works, the voltages on the those two lines would have to be within, oh, plus or minus 10% or strange things would start happening

    IF you the voltages were as you indicate, a switching supply probably wouldn't even tick over.
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

  6. #6

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    incorrect fuse in the volt meter, replaced it with a correct one, now it shows up to 4.9v, and 12.2v.
    "I think computer viruses should count as life. I think it says something about human nature that the only form of life we have created so far is purely destructive. We've created life in our own image." - Steven Hawking

  7. #7
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    Quote Originally Posted by squirrel-steam View Post
    incorrect fuse in the volt meter, replaced it with a correct one, now it shows up to 4.9v, and 12.2v.
    Much better.
    Legacy Computers and Parts

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  8. #8
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    Quote Originally Posted by squirrel-steam View Post
    I'll have to check that meter with another power supply. It might be bad, but its a 1500 dollar one my dad had from when he worked at waterlift (where they made the legs for the lunar lander.)
    Quote Originally Posted by squirrel-steam View Post
    incorrect fuse in the volt meter, replaced it with a correct one, now it shows up to 4.9v, and 12.2v.
    Well, that explains some of the problems that NASA had with the Lunar Lander all those years ago.

  9. #9

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    Quote Originally Posted by squirrel-steam View Post
    incorrect fuse in the volt meter, replaced it with a correct one, now it shows up to 4.9v, and 12.2v.
    Hi
    I'd love to know how a fuse can effect the voltage read by a meter??
    Dwight

  10. #10
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    Well, I was thinking about that too, and, the only thing I could think of would be a voltage divider set up by the resistor in a slo-blo fuse.
    Legacy Computers and Parts

    Sales of, parts for, and repairs to, Vintage and Legacy computers.

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