Dead Power Supplies...

Discussion in 'PC Hardware' started by RASelkirk, Jun 2, 2015.

  1. RASelkirk

    RASelkirk MDL Member

    Feb 4, 2010
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    Hi All,

    I managed to lose 2 computers today after a 1.5 hr power failure. My old XP box has been through dozens of PF's without a problem (until today), more on that in a minute. My Win7 box (HP500B) has had a weak PS for a year or so, meaning that after a PF and subsequent "cool down", it would fail to start. I could coerce it back to life by running a hair dryer through the PS fan for a minute or so, then it would start OK. About 6 months back, I bought a new PS for the HP knowing I would change it at the next opportunity (which came today). After the swap, I get virtually nothing. the PS green light is on and the fan runs, but no post up, no video, no beeps, no power light on the box. I checked this "new" PS with a tester and there is no light on the -5V line. Put the old PS in, heated it with the hair dryer, and get the exact same problem. Check it with the tester and get no light on the -5V. Gave up on the HP, went to the XP box in the back room, started it up, and it's doing the same f'ing thing! No video, no post, no beeps. Haven't checked that PS yet, got the red-ass and quit for the day. :mad: Maybe tomorrow will offer better insight...

    One oddity to note: In HP's hardware PDF, the 4-pin power connector shows the two black wires facing the fan, but on my MOBO the yellow wires are facing the fan. This connector does only go in one way, right?

    And WTF is on this -5V line?

    Russ
     
  2. RASelkirk

    RASelkirk MDL Member

    Feb 4, 2010
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    Did some more reading, the -5V line is considered "optional" on some power supplies. This is no help at all. Also found I can plug the 4-pin power connector in as shown in the PDF pic, but it's not easy and needs some force. Have not tried booting with it this way for fear of damage.

    Q on the CMOS battery. Computer should boot even w/o the battery, right? Should just boot to default settings, so even a dead battery should still allow a boot?

    Russ
     
  3. RASelkirk

    RASelkirk MDL Member

    Feb 4, 2010
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    OK. Found out the PS label shows what types of power it supplies and -5V is not one of them, so PS is good. Power up has a solid green LED on the PS, all fans spin up, nothing else happens. Time for a new box...

    Russ
     
  4. piercekalton

    piercekalton MDL Member

    Apr 2, 2010
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    NO! heat + computer = bad
     
  5. piercekalton

    piercekalton MDL Member

    Apr 2, 2010
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    MAYBE but disconnect the hard drive first and go straight to bios. just go buy a battery.
     
  6. zen45

    zen45 MDL Senior Member

    Feb 25, 2010
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    cmos

    you need that battery for it to read the bios so it knows what drive to boot from, also how about does it beep once when you start it that tells you all is well ! does it beep at all