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How to turn on an AT power supply?

Discussion in 'General Electronics' started by www.ChantCd.com, Jul 23, 2004.

  1. (I was trying to use an ATX supply before, but it seemed more complicated,
    so...)

    There is a switch on this AT-style power supply that I have now (of course).

    I stripped off the ends of one of the hard drive connectors, making sure
    they
    don't touch when I hit the power switch.

    I hit the switch, and nothing happens.

    Do I have a bad power supply? Or do you have to have a load of some kind for
    it to work? I'm just trying to turn it on with nothing - so I can measure
    the voltage
    with a VOM. Starting at the beginning, as it were.

    The other day, I was diagnosing a friend's bad PC - it turned out to be a
    bad power supply. (ATX)
    The way I found out? I just plugged the AT power supply to the hard drive
    (which wasn't spinning up, BTW) and turned it on - voila! The hard drive
    spun up. By this I guessed that the power supply was bad (turned out to be
    the case).
    My point is, I had just 1 hard drive as a load, and the thing powered up
    just fine.
    (I'm pretty sure it's the same power supply, too)

    Matthew
     
  2. Many - especially old AT - power supplies need some load to start and often
    some more load to stay stable. 12V car lamps or old HDDs often do a good job
    as a dummy load.

    petrus bitbyter
     
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