strange...

Discussion in 'Computer Information' started by TechRepair, Oct 22, 2003.

  1. TechRepair

    TechRepair Guest

    Hello all,

    Have this strange problem. I have a computer that will POST sometimes then
    it will freeze and other times it will freeze before POST. It is an ATX MB.
    I have tested the PS both on the molex plugs and they test at the correct
    voltage. I have tested the PS plug to the MB and each wire tests fine both
    with the power on, and the power off (with power to the PS on) The memory
    test good and I'm starting to think that the CPU is going bad? In all my
    years as a repair tech Ive never seen this... The known history of this
    system is it has been left on for long periods of time with a bad CPU fan...

    What do you all think?


    Thanks in advance,

    David Meek
     
    TechRepair, Oct 22, 2003
    #1
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  2. TechRepair

    Spajky Guest

    check the caps around socket or voltage regulators on MoBo !

    -- Regards, SPAJKY
    & visit site - http://www.spajky.vze.com
    Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
    E-mail AntiSpam: remove ##
     
    Spajky, Oct 22, 2003
    #2
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  3. TechRepair

    Firebird81 Guest

    If it's been left on for long periods of time with a bad CPU fan, there
    could be CPU damage, without a doubt. Swap it out for another CPU and see if
    it solves your problem. You did replace the bad fan I assume, correct? If it
    locks does it take several minutes before you can re-boot, or can you
    re-boot immediately?
     
    Firebird81, Oct 22, 2003
    #3
  4. TechRepair

    TechRepair Guest

    Oddly enough, the fan was replaced about 2 months ago and booted fine at
    that time. I suppose the owner could have zapped it with an ungrounded
    finger or something...
     
    TechRepair, Oct 22, 2003
    #4
  5. TechRepair

    Thor Guest

    That's an ok suggestion, but at least tell the guy what he should look for.
    Suspect capacitors (barrel-shaped objects) that have bulged tops (normal
    caps should be very flat on top), or brownish fluid leaking from the top or
    bottom of the capacitor.
     
    Thor, Oct 22, 2003
    #5
  6. TechRepair

    Spajky Guest

    Thought was enough because he said he is not a novice in matter ...

    -- Regards, SPAJKY
    & visit site - http://www.spajky.vze.com
    Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
    E-mail AntiSpam: remove ##
     
    Spajky, Oct 22, 2003
    #6
  7. TechRepair

    Thor Guest

    "Experienced" as a PC tech, doesn't always mean that a person is experienced
    much, or at all at the component-level, and may not notice something as
    subtle as a slightly-bulged capacitor top.
     
    Thor, Oct 22, 2003
    #7
  8. TechRepair

    TechRepair Guest

    You are right. I might not notice a bad capacitor right away because there
    is a laundry list of components that typically will fail long BEFORE a
    capacitor might. Unless during production it got to hot during the soldering
    process... I'm starting to think that it is the CPU.
     
    TechRepair, Oct 22, 2003
    #8
  9. TechRepair

    Thor Guest

    Thought was enough because he said he is not a novice in matter ...
    Yes, but realize that we are referring to capacitors that fail prematurely
    because they may be from a batch that were manufactured with faulty
    materials. Many major brands of motherboards have been affected by this
    problem that originated roughly 4 years ago, with a company that used stolen
    (and incomplete) information to manufacture electrolyte fluid, which they in
    turn sold to a few major Taiwanese capacitor manufacturers, who in turn sold
    these little ticking time-bomb caps to many major motherboard manufacturers.
    Asus, Abit, Gigabyte MSI, Biostar, IBM are just a few companies who had
    problems with these things. I've already fixed a few boards with this
    problem (because I am fairly skilled at component-level parts replacement,
    and the parts are cheap) The faulty electrolyte fluid releases hydrogen,
    which bulges or bursts the top or bottom of the cap, causing fluid leakage,
    and malfunction. Usually the symptom is a failure to post. Or a sudden
    lockup in windows, then a failure to post when reset.
     
    Thor, Oct 23, 2003
    #9
  10. TechRepair

    Plato Guest

    Sounds like VD aka a STD. [grin]

    My pre-emptive fluid is usually clear drops.
     
    Plato, Oct 23, 2003
    #10
  11. TechRepair

    TechRepair Guest

    Thanks a lot for the information... you've given me something new to think
    about and watch for in the future. I gave the MB a close examination and
    the tops of nearly all the capacitors are rounded or slightly rounded. I
    know that this computer was run for long periods of time with a bad CPU fan.

    Thank you all for your ideas

    Dave
     
    TechRepair, Oct 25, 2003
    #11
  12. TechRepair

    Thor Guest

    fan.

    It may or may not be the CPU at fault, but the caps should not have rounded
    tops. They should be flat. Rounded tops may indicate that they have built up
    abnormal pressure causing the top to bulge slightly, and as such may well be
    suspect for the problem I described.

    There is useful info about this problem here:

    http://www.justrepairs.com/capacitor_mb.html

    http://www.motherboardrepair.com/index.php?sec=images
     
    Thor, Oct 25, 2003
    #12
  13. TechRepair

    V W Wall Guest

    I don't think I'd trust these guys. They seen to have a strange ides of what
    a capacitor does in a circuit. Quote from the site:

    "In the electrical circuit, the capacitor takes variations in the input and
    creates a regulated output. The difference between the input and output energy
    converts to heat within the capacitor."

    Also:

    "In a typical switching power supply electronic applications, the electrolytic
    capacitor takes delivered AC power and converts it to a constant voltage
    output." This guy seems to know what he's doing. His prices for capacitor kits seem
    reasonable, as well.

    Virg Wall
     
    V W Wall, Oct 25, 2003
    #13
  14. TechRepair

    Thor Guest

    Yeah, but I didn't mean to refer to those sites for the guy's electronics
    knowledge, but rather mainly for the pictures, and a description of the
    faulty caps and the symptoms, which seems to be accurate enough. I didn't
    delve into the other info on the site, I just pulled it up on google.
     
    Thor, Oct 25, 2003
    #14
  15. TechRepair

    TechRepair Guest

    I figured it was for the picks also... by the way fig 2 on the first site is
    exactly what they look like.

    Dave
     
    TechRepair, Oct 26, 2003
    #15
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