HP Pavilion 7800 CTO - Hewlett Packard

This is a discussion on HP Pavilion 7800 CTO - Hewlett Packard ; Hi, I am trying to debug an apparent power supply/motherboard problem on my sister-in-law's HP Pavilion 7800 CTO machine. Orginally, she was having problems where the machine would not power on when she hit the switch. I looked inside and ...

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Thread: HP Pavilion 7800 CTO

  1. HP Pavilion 7800 CTO

    Hi,

    I am trying to debug an apparent power supply/motherboard problem
    on my sister-in-law's HP Pavilion 7800 CTO machine. Orginally, she
    was having problems where the machine would not power on when she
    hit the switch. I looked inside and without really doing anything it
    started to work again for about a month. Then it has the same problem
    so I tried replacing the power supply. That worked for a short period
    of time (a couple of days) but then it just died hard and now there is
    nothing that can be done to boot it.

    The current situation is that when I hit the switch, the fan on the power
    supply does a very quick whirl and nothing happens. Subsequent pulses
    of the fan do nothing either. I took a volt-meter and looked at the
    20 pin power connector on the board while playing with the switch. At
    the start, the 5VSB signal is 5V so I know that there is power to the
    switch. I also see that the P_ON signal is high, which I understand is
    pulled up by a resistor in the supply. When I hit the switch, I see that
    the P_ON signal pulls low and stays low as should be. The P_OK
    signal is not okay, though, just 0V. It looks like the supply does not
    like something on the board - maybe a short? What other things would
    be worth looking at here? Or does it just mean a bad motherboard that
    I should replace? Sounds from another thread like that could end up
    an O/S headache.

    Thanks,
    Tim



  2. Re: HP Pavilion 7800 CTO

    "TPM" a écrit dans le message de news:
    aKCdnYgqrur-tAjenZ2dnUVZ_sSdnZ2d@comcast.com...
    > Hi,
    >
    > I am trying to debug an apparent power supply/motherboard problem
    > on my sister-in-law's HP Pavilion 7800 CTO machine. Orginally, she
    > was having problems where the machine would not power on when she
    > hit the switch. I looked inside and without really doing anything
    > it
    > started to work again for about a month. Then it has the same
    > problem
    > so I tried replacing the power supply. That worked for a short
    > period
    > of time (a couple of days) but then it just died hard and now there
    > is
    > nothing that can be done to boot it.
    >
    > The current situation is that when I hit the switch, the fan on the
    > power
    > supply does a very quick whirl and nothing happens. Subsequent
    > pulses
    > of the fan do nothing either. I took a volt-meter and looked at the
    > 20 pin power connector on the board while playing with the switch.
    > At
    > the start, the 5VSB signal is 5V so I know that there is power to
    > the
    > switch. I also see that the P_ON signal is high, which I understand
    > is
    > pulled up by a resistor in the supply. When I hit the switch, I see
    > that
    > the P_ON signal pulls low and stays low as should be. The P_OK
    > signal is not okay, though, just 0V. It looks like the supply does
    > not
    > like something on the board - maybe a short? What other things
    > would
    > be worth looking at here? Or does it just mean a bad motherboard
    > that
    > I should replace? Sounds from another thread like that could end up
    > an O/S headache.
    >
    > Thanks,
    > Tim
    >


    Tried removing and putting back every parts on the motherboard. For
    example, on my desktop computer, once, it didn't want to boot up, I
    removed and replace the memory and it worked back.

    Deko



  3. Re: HP Pavilion 7800 CTO


    "Deko" wrote in message
    news:FRflf.7375$z5.72285@wagner.videotron.net...
    > "TPM" a écrit dans le message de news:
    > aKCdnYgqrur-tAjenZ2dnUVZ_sSdnZ2d@comcast.com...
    >> Hi,
    >>
    >> I am trying to debug an apparent power supply/motherboard problem
    >> on my sister-in-law's HP Pavilion 7800 CTO machine. Orginally, she
    >> was having problems where the machine would not power on when she
    >> hit the switch. I looked inside and without really doing anything it
    >> started to work again for about a month. Then it has the same problem
    >> so I tried replacing the power supply. That worked for a short period
    >> of time (a couple of days) but then it just died hard and now there is
    >> nothing that can be done to boot it.
    >>
    >> The current situation is that when I hit the switch, the fan on the power
    >> supply does a very quick whirl and nothing happens. Subsequent pulses
    >> of the fan do nothing either. I took a volt-meter and looked at the
    >> 20 pin power connector on the board while playing with the switch. At
    >> the start, the 5VSB signal is 5V so I know that there is power to the
    >> switch. I also see that the P_ON signal is high, which I understand is
    >> pulled up by a resistor in the supply. When I hit the switch, I see that
    >> the P_ON signal pulls low and stays low as should be. The P_OK
    >> signal is not okay, though, just 0V. It looks like the supply does not
    >> like something on the board - maybe a short? What other things would
    >> be worth looking at here? Or does it just mean a bad motherboard that
    >> I should replace? Sounds from another thread like that could end up
    >> an O/S headache.
    >>
    >> Thanks,
    >> Tim
    >>

    >
    > Tried removing and putting back every parts on the motherboard. For
    > example, on my desktop computer, once, it didn't want to boot up, I
    > removed and replace the memory and it worked back.
    >
    > Deko
    >


    Thanks for the advice. I have actually tried that and it does not seem to
    have helped but I will play with it a bit more.

    Tim



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