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Power supply testing

Discussion in 'General Hardware' started by viczulis, Sep 25, 2011.

  1. viczulis

    viczulis New Member

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    Heres what I got. I have a 500 watt power supply that wont power up two different towers.
    The towers are pretty basic ones a P4 with AGP video card one hard drive, the other is a basic board with on board video and one hard drive, each have a DVD burner and thats about it. Nothing special or power demanding.
    I have a digital tester and everything test good. 20 pin, 24 pin, 4 pin power, all satas, all molexes.
    You turn either computer on fans spin but nothing comes up on screen. I connect my 650 watt supply in and both towers fire up.

    How would you test under load it has to be failing there but I dont know how to test.

    :banghead:
  2. sneekypeet

    sneekypeet Unpaid Babysitter Staff Member

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    connect a fan and a fan controller?

    Connect it to anything that draws 12V, 5V and 3.3V so you can check with a DMM whats being pushed. my guess is a weak 5V line.
    coljarcker and viczulis say thanks.
  3. cdawall where the hell are my stars

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    hook some fans up to the molex's big fans work better.
    viczulis says thanks.
  4. viczulis

    viczulis New Member

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    Will try. Thanks guys :toast:

    Okay got five 120 fans running with no problems thats all I have with molex getting reading of 5.2 got to find cables to turn three pins into molex to keep going.
    Last edited: Sep 25, 2011
  5. sneekypeet

    sneekypeet Unpaid Babysitter Staff Member

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    daisy chain more fans or add some sort of 12V device to a line to keep a bigger draw on it. See if the line drops out. Something has to be going on near the higher end of the power band.

    If you are brave, open it up and see if the caps inside are all good, and maybe clean out anything that may be adding resistance inside the PSU.

    I'm guessing each fan is under an amp a piece, so even though they are running it doesn't produce anywhere near the draw of the PC.
  6. viczulis

    viczulis New Member

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    One 12 volt line drops have DVD drives on when opening doors with all fans running it goes from 12.1 to 12.0 will have to find more to draw some power. Dam it cant be easy :laugh:

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