#PS_ON always low-signal (PSU keeps running)

Discussion in 'Asus' started by Stefan Heinrichsen, Jul 14, 2007.

  1. Hello,

    my Asus A8N SLI Deluxe always has a low-signal on #PS_ON. So my PSU never
    shuts down. When shutting down the Computer the USB-Connectors turn off,
    Monitors goes to Stand-By,... but PSU and it connected coolers ar still
    running. Than it is even not possible to shut the PC on again with the
    normal Powerbutton. The only way to turn the PC off or on again is using
    the switch on the backside of the PSU.
    So I measured the #PS_ON signal and it is constant 0,7 Volt, so means a low
    signal which tells the PSU to Power-On.
    This is not depending on the OS (tested with Linux + Windows), not depending
    on the PSU (tested with 3 working PSUs) and not depending on other hardware
    (tested with only MB+PSU connected).

    Stefan
     
    Stefan Heinrichsen, Jul 14, 2007
    #1
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  2. Stefan Heinrichsen

    Oldish Git Guest

    Sounds like a fault on the mobo then. I suppose you
    could always fit a manual on/off switch on that line,
    and operate it after windows has shut down.
    As to a mobo fault, maybe a bad sensor is seeing high
    temps and keeping the fans going until it cools (which
    it obviously doesn't.) Have a look at what the bios
    temp readings are and see if any are way out.
    Might be worth a fiddle with bios power settings, too.
    Pure guesswork, btw - I've not come across this one
    before.
    HTH,
     
    Oldish Git, Jul 14, 2007
    #2
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  3. Stefan Heinrichsen

    Bill Jemison Guest

    I recently experienced an intermittent problem with a homebuilt computer
    where the system wouldn't completely shut down (case fan would keep
    running and keyboard would appear to have power).

    After a bunch of research, I tore the system apart and reinstalled cpu,
    memory, boards .... on the assumption that the power problem was related
    to a bad connection. It seems to have worked.

    It may be worth a try to rule out a simple "bad connection" kind of problem.

    Good luck.

    Bill
     
    Bill Jemison, Jul 15, 2007
    #3
  4. Helo,

    The anoying is that I still would always have to wait until Windows/Linux is
    down and than press this button.
    I nice workaround would be to have a circuit which measures the power for
    example at USB and if it's down switch the line of and (like usualy) on
    again when powerbutton is pressed. But therefore my knowledge of
    electrotechnology is to little.
    I had a look and all sensor have good values (about 35°C / 95°F)
    Even already tried this. But I also resetet and updated the BIOS already so
    I don't think there is anything misconfigured.

    Thanks
    Stefan
     
    Stefan Heinrichsen, Jul 15, 2007
    #4
  5. The only thing I didn't reinstalled yet was the CPU so I gave it a try
    reinstalling it but it even didn't helped.

    Stefan
     
    Stefan Heinrichsen, Jul 15, 2007
    #5
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