Motherboard Problem

Discussion in 'Computer Information' started by Thomas, Dec 11, 2007.

  1. Thomas

    Thomas Guest

    Hello. I turned on my desktop the other day and it shut off and then I
    noticed a puff of smoke and a bad smell. I thought the power supply burned
    out even though it was only 3 months old. I went out and bought another one
    exactly like the other one and installed it and the same thing happened. I
    know now the smoke came off the motherboard. I saw it the second time. Do
    you think that the motherboard problem has destroyed both power supplies? I
    plugged them directly into the wall hoping to see the fan turn but nothing
    happened. Should the fan turn when plugged straight into the wall and does
    that mean that the power supplies are both shot now? Thanks.

    Thomas
    Thomas, Dec 11, 2007
    #1
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  2. Thomas

    Paul Guest

    Thomas wrote:
    > Hello. I turned on my desktop the other day and it shut off and then I
    > noticed a puff of smoke and a bad smell. I thought the power supply burned
    > out even though it was only 3 months old. I went out and bought another one
    > exactly like the other one and installed it and the same thing happened. I
    > know now the smoke came off the motherboard. I saw it the second time. Do
    > you think that the motherboard problem has destroyed both power supplies? I
    > plugged them directly into the wall hoping to see the fan turn but nothing
    > happened. Should the fan turn when plugged straight into the wall and does
    > that mean that the power supplies are both shot now? Thanks.
    >
    > Thomas
    >
    >


    The power supply will not run, when it is sitting all by itself
    on your table top. To run, you have to connect PS_ON# to COM,
    on the main power connector. That is what the motherboard does,
    when the motherboard wants the power supply to turn on. When
    PS_ON# is connected to COM (ground), that causes all the
    "soft power" voltages to operate, and the power supply fan
    to spin.

    The power supply does have a standby voltage, called +5VSB, and
    that is a source of power for when the computer is sleeping.
    It is present as long as the switch on the back is set to ON.
    It also powers the circuit that handles switching on the rest
    of the power supply. On an Asus motherboard, that is what makes
    the green LED on the motherboard surface, to glow.

    To test a power supply, you can use a gadget like this, as it
    puts a small load on the supply, and connects PS_ON# to COM.
    In addition to one of these, a multimeter (available at Radio Shack
    or the hardware store), can be used to verify the voltages on the
    main connector. That is to help assure you the supply is really
    working. Check to see if the +3.3V, +5V, +12V, -12V, +5VSB, are
    all operating properly or not.

    http://www.startech.com/Product/ItemDetail.aspx?productid=PSUTEST20&c=CA

    Pinout for ATX is here. 24 pin and 20 pin types.

    http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf
    http://www.formfactors.org/developer/specs/atx/ATX12V_1_3dg.pdf

    Paul
    Paul, Dec 11, 2007
    #2
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  3. Thomas

    Thomas Guest

    "Paul" <> wrote in message news:fjl5cd$geg$...
    > Thomas wrote:
    >> Hello. I turned on my desktop the other day and it shut off and then I
    >> noticed a puff of smoke and a bad smell. I thought the power supply
    >> burned out even though it was only 3 months old. I went out and bought
    >> another one exactly like the other one and installed it and the same
    >> thing happened. I know now the smoke came off the motherboard. I saw it
    >> the second time. Do you think that the motherboard problem has destroyed
    >> both power supplies? I plugged them directly into the wall hoping to see
    >> the fan turn but nothing happened. Should the fan turn when plugged
    >> straight into the wall and does that mean that the power supplies are
    >> both shot now? Thanks.
    >>
    >> Thomas

    >
    > The power supply will not run, when it is sitting all by itself
    > on your table top. To run, you have to connect PS_ON# to COM,
    > on the main power connector. That is what the motherboard does,
    > when the motherboard wants the power supply to turn on. When
    > PS_ON# is connected to COM (ground), that causes all the
    > "soft power" voltages to operate, and the power supply fan
    > to spin.
    >
    > The power supply does have a standby voltage, called +5VSB, and
    > that is a source of power for when the computer is sleeping.
    > It is present as long as the switch on the back is set to ON.
    > It also powers the circuit that handles switching on the rest
    > of the power supply. On an Asus motherboard, that is what makes
    > the green LED on the motherboard surface, to glow.
    >
    > To test a power supply, you can use a gadget like this, as it
    > puts a small load on the supply, and connects PS_ON# to COM.
    > In addition to one of these, a multimeter (available at Radio Shack
    > or the hardware store), can be used to verify the voltages on the
    > main connector. That is to help assure you the supply is really
    > working. Check to see if the +3.3V, +5V, +12V, -12V, +5VSB, are
    > all operating properly or not.
    >
    > http://www.startech.com/Product/ItemDetail.aspx?productid=PSUTEST20&c=CA
    >
    > Pinout for ATX is here. 24 pin and 20 pin types.
    >
    > http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf
    > http://www.formfactors.org/developer/specs/atx/ATX12V_1_3dg.pdf
    >
    > Paul
    Thomas, Dec 12, 2007
    #3
  4. The fans do not run when the power supply is plugged into the wall. The
    computer sends an ON signal to the power supply to get a visible ON
    condition, otherwise you can not see the power supply operating.

    I'm not sure the power supply is toast, but the magic smoke leaking from the
    motherboard is never a good sign. Computers work by magic smoke, and yours
    has leaked out so I do not hold much hope for it to work again.



    "Thomas" <> wrote in message
    news:Kno7j.6727$...
    > Hello. I turned on my desktop the other day and it shut off and then I
    > noticed a puff of smoke and a bad smell. I thought the power supply
    > burned out even though it was only 3 months old. I went out and bought
    > another one exactly like the other one and installed it and the same thing
    > happened. I know now the smoke came off the motherboard. I saw it the
    > second time. Do you think that the motherboard problem has destroyed both
    > power supplies? I plugged them directly into the wall hoping to see the
    > fan turn but nothing happened. Should the fan turn when plugged straight
    > into the wall and does that mean that the power supplies are both shot
    > now? Thanks.
    >
    > Thomas
    >
    Jeff Strickland, Dec 13, 2007
    #4
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