General Possibly dumb question....

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  • DixiePenguin
    Senior Member
    • Mar 2008
    • 77
    • Philippines
    #1

    General Possibly dumb question....

    Hey, I have just been testing some power supplies given to me and noticed something odd. I am using an older Power Judge as a basic first check. I am getting overvoltage on reading on all three newer power supplies that are missing the old -5v wire. Is the lack of this line triggering a false reading? The others are older supplies with the -5V line and all test fine. I took an older one with -5V which I knew was bad. I got the expected overvoltage. I dug out and looked at two others I had tested earlier and had given overvoltage warnings, you guessed it, both are minus -5V.

    It just doesn't seem I could have five bad supplies that all happen to be minus the -5V line. You guys know more on the inner workings and theories, I'm just a solder monkey. What do you think?

    Bill

    Supplies w/o -5V, giving overvoltage warning:

    Dell L280P-01 24pin
    Ultra ULT-XF700s (CyberPower OEM) 20/24pin
    Bestec ATX1956D 24pin
    Hercules 450W 20pin
    Hercules 480W 20/24pin

    Bad WITH -5V showing overvoltage:
    Antec SL300S 20pin
    Tags: None
    • DixiePenguin
      Senior Member
      • Mar 2008
      • 77
      • Philippines
      #2
      Re: General Possibly dumb question....

      Solved it myself. Answer is YES. Older Power Judge testers misread if there is no -5V wire present. I tested with a couple of junk supplies. Green across the board on the Power Judge I was using. I then clipped the wire to simulate the missing pin in newer supplies. Presto...overvoltage warning. Reconnect the wire, everything green again. Same results on second test supply.

        Comment

        • momaka
          master hoarder
          • May 2008
          • 12170
          • Bulgaria
          #3
          Re: General Possibly dumb question....

          PSU testers are not precise instruments so only use them to see if a PSU works (i.e. turns on). Always best to check the voltages with a multimeter if you want an accurate reading (the only better thing than that is an oscilloscope).

          Well, not much more to say. You did solve the problem yourself after all

            Comment

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