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NO POWER, Is it power supply or motherboard?

Discussion in 'Hardware' started by wiredawg, Nov 16, 2011.

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  1. wiredawg

    wiredawg Thread Starter

    Joined:
    Nov 14, 2011
    Messages:
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    HP Palvilion m9077c
    Motherboard IPIBL-LA (Berkeley)
    http://h10025.www1.hp.com/ewfrf/wc/...lc=en&lang=en&lc=en&product=3624429&task=#N72

    Power Supply (DPS-350ab-8a)
    http://www.itwinkle.com/hp35posu51.html

    Hello all, this is my first post. First, let me thank all for being here and sharing your vast knowledge. My PC and power supply is above, web-links included for more accurate description. Also, I have scoured this forum/internet attempting to resolved and yes there is a ton of info. The problem is the I cannot find specific details "similar" to my problem regarding how they determined the repair action, other than replaced power or mobo. So hopefully, when this is resolved this will help someone with my similar problem.

    - Problem > PC will not turn-on, just as if not plugged into power source.
    -- Sypnopsis > Nothing unusual happened as far as I know. Shut-down PC for the evening as
    usual, next day went to turn it on...nothing.

    - Troubleshooting accomplished:
    -- Checked power outlet & cords, checked good
    -- Green light on back of power supply is steady green...normal indication
    -- Removed power supply to test with multi-meter. Strapped/jumpered pins 16 (green wire) with
    ground (blk wire). All appears normal, everything is in range of specifications, values below:
    pin 1: 3.39
    pin 2: 3.39
    pin 4: 5.07
    pin 6: 5.07
    pin 8: 5.03
    pin 9: 5.03
    pin 10: 12.17
    pin 11: 3.39
    pin 12: 3.39
    pin 13: 3.39
    pin 14: (-)12.01
    pin 21: 5.07
    pin 22: 5.07
    pin 23: 5.07

    -- Tested my power button wires for continuity on PC case, properly shorts.
    -- Reassemble everything, still nothing
    -- Disassemble entire PC, motherboard is sitting on cardboard box.
    --- Items plugged into motherboard:
    1) 24-pin atx plug and from power supply
    2) 4-pin plug (12 volt) from power supply
    3) (1) 1gig ram stick
    4) CPU & CPU fan

    - Goal > power-on motherboard
    -- Tried shorting power button pins...nothing : (
    -- Tried shorting reset pins...nothing : (
    -- Jump-started atx plug with paper clip...POWERS ON!!! : ) See link below for example:

    http://www.youtube.com/watch?v=FCspIGgBV00&feature=related

    Unfortunately, unlike the youtube video; when I remove the paper clip I lose power and back to square one. : (

    - Back to the PS...tested PS with strap/jumper on, when I remove the strap the ATX loses power through its plugs, though the green light stays constant green. There is no external on/off switch on the power supply.

    -- Should the power supply lose power once the strap is removed?
    -- If so, how does the power supply know to stay on?
    -- Any help is much appreciated, trying to determine if power supply is bad, MOBO, etc and if I can repair it. Also, I cannot swap items, I do not have any additional parts laying around.

    ADDITONAL NOTES:
    - When powered on, the mobo pwr-btn pins and the reset pins have voltage accross them
    3.1 volts dc (pwr btn pins)...though, has "NO" effect when shorted
    3.3 volts dc (reset pins)...resets when shorted...it works the way it should

    - Attached additional items to see if I could fully boot PC
    5) System Fan (note: will not boot without this fan plugged-in. "ERROR: System Fan Has Failed. Service PC to prevent damage to the System. Press F2 to continue"
    6) video card (geforce gt 8500/hp pn-5188)
    7) key board (plugged into PS2/keyboard port)
    9) mouse (plugged into PS2/mouse port)
    10) Hard drive

    When strapped, I can boot competely up and log-on to desktop.
    When I choose "restart" via windows soft button, it resets properly.
    When I choose "shutdown" it will shutdown, but then I have to remove the strap and reset the cmos (I get no display, unless I reset the CMOS) to boot up properly again.

    I'm guessing, ultimately its the power supply. Since the problem directs back to losing power. The PC boots properly when I make the conditions right, so that would most likely eliminate a motherboard or cpu problem. What I don't understand, nor can I find any info on is; how does the power supply stay activate? I'm aware of the shorting of the power button pins on the mobo. Probably thinking too much into it, but the power supply seems to be working, accept for the mystery "no power switch" issue. I'm going to hunt down a power supply from somewhere and try it.

    Again, any help is much appreciated.
     
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  3. ekim68

    ekim68

    Joined:
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    52,441
    First Name:
    Mike
    Power supplies do wear out especially after 5 to 8 years of life....But, if you were able to get an 'error' message and hit 'F2 to continue' then the power supply was working....Have you tried to boot to a CD?
     
  4. wiredawg

    wiredawg Thread Starter

    Joined:
    Nov 14, 2011
    Messages:
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    @ ekim68, What would be the purpose of booting to a CD? I will try tomorrow, but I don't understand why.
     
  5. ekim68

    ekim68

    Joined:
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    Messages:
    52,441
    First Name:
    Mike
    That would tell you if it was the hard drive or the power supply....If you can get into the BIOS setup and allow a CD to boot the system then it would eliminate the power supply as the problem because it would allow you to do that..
     
  6. wiredawg

    wiredawg Thread Starter

    Joined:
    Nov 14, 2011
    Messages:
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    I still don't understand the logic, given I can access the bios with no hard drive attach. When I attach the hard drive, I can access the desktop. But, I will try...I just don't "get-it". : )
    And for clarification;
    1) I should access the bios and change the setting to boot to CD/DVD drive first?
    2) Attach my hard drive or not attach it?
    3) The CD or DVD should be a windows boot CD/DVD? I'm asking, what "data" should be on the cd/dvd? Also, I my normal system would be vista.
     
  7. wiredawg

    wiredawg Thread Starter

    Joined:
    Nov 14, 2011
    Messages:
    4
    Okay folks its not the power supply, power supply works fine in another machine. So, any thoughts on how to repair/figure out why the power pins do not power-on when shorted...I have to used to hard jumper on the 24-pin atx cable (grn & grnd) to power on the motherboard.
     
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