Can bad caps on a motherboard kill a PSU?

Discussion in 'PC Hardware' started by spodosaurus, Aug 12, 2007.

  1. spodosaurus

    spodosaurus Guest

    Hi all,

    In a recent thread here ("") I was testing out a new tool to quickly
    diagnose whether a PCs issues were PSU related. Turns out the power
    supply tester and the PSU were defective (behold the power and of the
    multimeter). Anyway, The Antec TruePower 380 PSU is only about 26 months
    old and seems a tad young to be dying seeing as my other Antec TruePower
    380 is over four years old and running perfectly. The motherboard in the
    system with the bad PSU is one of several Gigabyte boards I've owned
    that have been affected by the bad capacitor issue. I'm wondering if the
    buldging caps on the GA-7VTXE+ board could have caused the early demise
    of the 5V rail on the PSU?

    PSU readings on the 20 pin ATX connector:

    Pins 1, 2, and 11 (3.3V): 3.28V (good)
    Pins 4, 6, 19, and 20 (5V): 4.68V (bad)
    Pin 9 (5VSB): 5.05V steady (good)
    Pin 10 (12V): 11.66V (good)
    Pin 12 (-12V): -12.58V (good)

    Ari

    --
    spammage trappage: remove the underscores to reply
    Many people around the world are waiting for a marrow transplant. Please
    volunteer to be a marrow donor and literally save someone's life:
    http://www.abmdr.org.au/
    http://www.marrow.org/
     
    spodosaurus, Aug 12, 2007
    #1
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  2. spodosaurus

    Paul Guest

    spodosaurus wrote:
    > Hi all,
    >
    > In a recent thread here ("") I was testing out a new tool to quickly
    > diagnose whether a PCs issues were PSU related. Turns out the power
    > supply tester and the PSU were defective (behold the power and of the
    > multimeter). Anyway, The Antec TruePower 380 PSU is only about 26 months
    > old and seems a tad young to be dying seeing as my other Antec TruePower
    > 380 is over four years old and running perfectly. The motherboard in the
    > system with the bad PSU is one of several Gigabyte boards I've owned
    > that have been affected by the bad capacitor issue. I'm wondering if the
    > buldging caps on the GA-7VTXE+ board could have caused the early demise
    > of the 5V rail on the PSU?
    >
    > PSU readings on the 20 pin ATX connector:
    >
    > Pins 1, 2, and 11 (3.3V): 3.28V (good)
    > Pins 4, 6, 19, and 20 (5V): 4.68V (bad)
    > Pin 9 (5VSB): 5.05V steady (good)
    > Pin 10 (12V): 11.66V (good)
    > Pin 12 (-12V): -12.58V (good)
    >
    > Ari
    >


    (Your motherboard ?)
    http://www.fmc.com.tw/product/gigamb/pic/7vtxe .jpg

    Does the voltage on the 5V rail, pop up to normal levels
    if the supply is not powering that particular motherboard ?

    It could be that the 4.68V level is there, because an extreme
    amount of amps are being drawn. That is one reason I like to
    have a clamp-on DC ammeter, to quickly check the current draw,
    and detect an overload in progress. What you do with the clamp-on
    ammeter, is open the jaws, and place the jaws around all the
    5V wires at the same time. The clamp-on ammeter can sum the
    current flow in all the wires, and give a total 5V ampere reading
    flowing into the motherboard. And because the meter is non-contact,
    you don't need to cut wires or anything. The meter uses Hall Probe
    technology, and senses the magnetic field. The only caveat, is
    limited bandwidth, and the inability to handle complex AC
    waveforms properly (does a lousy job of measuring standby power
    flowing in the AC line cord).

    A 60W Athlon would be 5V @ 12A. The Vcore converter is 90% efficient
    or less, so the amps need to be bumped to 12/0.90 = 13.3 amps. So,
    if measuring the 5V into the board, I'd expect to see a bit more
    current than that, when the board is running Prime95 or CPUBurn.
    How much more than 13.3 amps, depends on what other stuff runs
    off +5V.

    This is my meter. The 40 amps DC range is good for motherboards.
    I use the 400 amp DC range, to work on my car :) Normal multimeter
    current ranges, seldom exceed about 10 amps. These are very handy
    to have, and if your business has a budget for test equipment,
    add one to the bench.

    http://exphil.com/images/products/Extech/380947.jpg

    The lifetime of a power supply, could be affected by the load
    placed on it. Some of the Antec supplies are known to use a
    poor brand of caps. All capacitors are sensitive to temperature,
    and the higher the temp, the faster they dry out. Which is
    one reason I am not happy to see the fan spin so slow on some
    power supplies. Higher fan speed means lower internal PSU
    temp and longer life.

    Paul
     
    Paul, Aug 12, 2007
    #2
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  3. spodosaurus

    spodosaurus Guest

    Paul wrote:
    > spodosaurus wrote:
    >> Hi all,
    >>
    >> In a recent thread here ("") I was testing out a new tool to quickly
    >> diagnose whether a PCs issues were PSU related. Turns out the power
    >> supply tester and the PSU were defective (behold the power and of the
    >> multimeter). Anyway, The Antec TruePower 380 PSU is only about 26
    >> months old and seems a tad young to be dying seeing as my other Antec
    >> TruePower 380 is over four years old and running perfectly. The
    >> motherboard in the system with the bad PSU is one of several Gigabyte
    >> boards I've owned that have been affected by the bad capacitor issue.
    >> I'm wondering if the buldging caps on the GA-7VTXE+ board could have
    >> caused the early demise of the 5V rail on the PSU?
    >>
    >> PSU readings on the 20 pin ATX connector:
    >>
    >> Pins 1, 2, and 11 (3.3V): 3.28V (good)
    >> Pins 4, 6, 19, and 20 (5V): 4.68V (bad)
    >> Pin 9 (5VSB): 5.05V steady (good)
    >> Pin 10 (12V): 11.66V (good)
    >> Pin 12 (-12V): -12.58V (good)
    >>
    >> Ari
    >>

    >
    > (Your motherboard ?)
    > http://www.fmc.com.tw/product/gigamb/pic/7vtxe .jpg
    >


    Yes


    > Does the voltage on the 5V rail, pop up to normal levels
    > if the supply is not powering that particular motherboard ?


    No. Same if it's powering the power supply tester and IDE drives, or
    just the paperclip jumper method + IDE drives.

    > A 60W Athlon would be 5V @ 12A.


    Athlon XP 2400+

    > The lifetime of a power supply, could be affected by the load
    > placed on it. Some of the Antec supplies are known to use a
    > poor brand of caps. All capacitors are sensitive to temperature,
    > and the higher the temp, the faster they dry out. Which is
    > one reason I am not happy to see the fan spin so slow on some
    > power supplies. Higher fan speed means lower internal PSU
    > temp and longer life.


    The fan in this PSU spins at a constant speed (I don't even think this
    PSU has the fan throttling circuitry and the motherboard connector that
    the TruePower II series has). The case also has a small rear exhaust fan
    (60mm Vantec Stealth) so ventilation could be better.

    Ari


    --
    spammage trappage: remove the underscores to reply
    Many people around the world are waiting for a marrow transplant. Please
    volunteer to be a marrow donor and literally save someone's life:
    http://www.abmdr.org.au/
    http://www.marrow.org/
     
    spodosaurus, Aug 12, 2007
    #3
  4. spodosaurus

    Paul Guest

    spodosaurus wrote:
    > Paul wrote:
    >> spodosaurus wrote:
    >>> Hi all,
    >>>
    >>> In a recent thread here ("") I was testing out a new tool to quickly
    >>> diagnose whether a PCs issues were PSU related. Turns out the power
    >>> supply tester and the PSU were defective (behold the power and of the
    >>> multimeter). Anyway, The Antec TruePower 380 PSU is only about 26
    >>> months old and seems a tad young to be dying seeing as my other Antec
    >>> TruePower 380 is over four years old and running perfectly. The
    >>> motherboard in the system with the bad PSU is one of several Gigabyte
    >>> boards I've owned that have been affected by the bad capacitor issue.
    >>> I'm wondering if the buldging caps on the GA-7VTXE+ board could have
    >>> caused the early demise of the 5V rail on the PSU?
    >>>
    >>> PSU readings on the 20 pin ATX connector:
    >>>
    >>> Pins 1, 2, and 11 (3.3V): 3.28V (good)
    >>> Pins 4, 6, 19, and 20 (5V): 4.68V (bad)
    >>> Pin 9 (5VSB): 5.05V steady (good)
    >>> Pin 10 (12V): 11.66V (good)
    >>> Pin 12 (-12V): -12.58V (good)
    >>>
    >>> Ari
    >>>

    >>
    >> (Your motherboard ?)
    >> http://www.fmc.com.tw/product/gigamb/pic/7vtxe .jpg
    >>

    >
    > Yes
    >
    >
    >> Does the voltage on the 5V rail, pop up to normal levels
    >> if the supply is not powering that particular motherboard ?

    >
    > No. Same if it's powering the power supply tester and IDE drives, or
    > just the paperclip jumper method + IDE drives.
    >
    >> A 60W Athlon would be 5V @ 12A.

    >
    > Athlon XP 2400+
    >
    >> The lifetime of a power supply, could be affected by the load
    >> placed on it. Some of the Antec supplies are known to use a
    >> poor brand of caps. All capacitors are sensitive to temperature,
    >> and the higher the temp, the faster they dry out. Which is
    >> one reason I am not happy to see the fan spin so slow on some
    >> power supplies. Higher fan speed means lower internal PSU
    >> temp and longer life.

    >
    > The fan in this PSU spins at a constant speed (I don't even think this
    > PSU has the fan throttling circuitry and the motherboard connector that
    > the TruePower II series has). The case also has a small rear exhaust fan
    > (60mm Vantec Stealth) so ventilation could be better.
    >
    > Ari
    >


    If the voltage had popped up, under no load, that would suggest that
    the computer was loading the thing heavily. If the voltage is relatively
    the same, with a load connected, or with no load, that tends to suggest
    the supply for some reason, is always outputting on the low side.

    4.68V is out of spec, so I'd replace it. Ideally, the supply should
    have some loading on it, in case the design is such that it goes out
    of regulation when the minimum current loading is not provided. But
    since you've measure the voltage while in-circuit and got 4.68V,
    then I'd change it out.

    I do occasionally replace supplies, before they have a chance to fail.
    On my first home build, I swapped out the supply when the fans started
    to run erratically. A sign that the 12V was starting to "wobble".
    That supply still works, but I won't be using it again. Using the
    multimeter, I think it is still in spec - I just don't like to see
    a supply that changes output voltage for no reason. (I.e. Fan speed
    would change while sitting in the BIOS.)

    Paul
     
    Paul, Aug 12, 2007
    #4
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