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Help Diagnosing a possible psu failiure

Discussion in 'Hardware' started by Kierax, 18 Jun 2008.

  1. Kierax

    Kierax What's a Dremel?

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    HI

    I am reasonably sure this is a PSU fail. My Seasonic S12 power unit is about two years old, and runs a 3.2GHZ Q6600 based system with a OC"d 8800GTS 512MB. Recently been in storage for a few weeks since we thought we had to sell it, I took it out today, never being took away from room temperature or subject to any shocks I was suprised when NOTHING happened.

    I changed the power leads for the one in the tft which obviously worked and still nothing, nothing in the sense of the psu did not make a noise, the fan didnt spin, and the motherboard and NO lights on at all as if no power was getting through.

    Now the psu is quite dusty inside and I am wary of opening it up, but I have no warranty on it so could it be the dust or is it better to just buy a brand new one? I've under £100 and I'd like something modular but will take normal for the reliability and brand name.

    Really stumped as to how it has died on me while doing nothing... sods law eh?:rolleyes:
     
  2. chrisb2e9

    chrisb2e9 Dont do that...

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    outlet has power? switch on the psu turned on? correct voltage setting on the psu?
    and I cant remember how to do it but you can short out two leads to turn on the psu manually. its somewhere in the forums.

    thats about all I can think of. Short of trying a different psu in the same pc.
     
  3. Kierax

    Kierax What's a Dremel?

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    Power is on

    PSU turned on yes

    No voltage options on mine UK only

    NO idea how to short it... could be two leads contacting you could have a point... but I very much doubt it
     
  4. Glider

    Glider /dev/null

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    IIRC green and black in the ATX plug
     
  5. Kierax

    Kierax What's a Dremel?

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    And what would that do :O
     
  6. hitman012

    hitman012 Minimodder

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    Shorting green to black (ground) on the main ATX connector will tell the PSU to start. You can do that to see if it works when it's not connected to the motherboard. If it does, the problem is likely to be elsewhere in the machine. I would plug it into some fans or drives to load it slightly before you try that trick.

    If you have a multimeter, also try measuring the voltage between the purple wire and ground. That particular pin supplies standby power to the motherboard and should be at about 5 volts regardless of whether the PSU is on or off (though obviously the mains needs to be on). If it's not, you've probably got a dead supply. It's also worth checking the voltage at the grey wire, which is a signal to the motherboard that the power supply is ready to start. Again, if that's not at 5V or thereabouts, there's a problem with the supply.

    Edit: Here's a pinout of the main ATX connector: http://wiki.xtronics.com/index.php/ATX_Pinout
     
    Last edited: 18 Jun 2008
  7. Kierax

    Kierax What's a Dremel?

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    I have to say I am not comfortable doing that, and I think my GF would have my head.


    edit: I have noticed on the 24pin plug it appears one of the slots has NO connector inside, is this a normal thing or sign of the possible problem?
     
  8. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    That's normal. Not all of the pins are connected.
     
  9. hitman012

    hitman012 Minimodder

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    Can you post which pin it is? It's probably just a ground. I've seen those missed out on supplies before.

    If you're not comfortable with shorting the pins on the PSU (which is totally safe - the voltages on the DC side of the unit are much too low to cause any injury) you could probably buy a power supply tester of some sort (like this or this).
     
  10. Kierax

    Kierax What's a Dremel?

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    I've taken the ram and gfx off the power unit and still nothing, the missing pin seems normal no wire goes to it.

    GF is willing to let me buy a Corsair HX620 power unit since the Seasonic S12 I have now is well over a year old if not two years old..
     
  11. hitman012

    hitman012 Minimodder

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    Sounds stupid, but it might be worth quickly double checking that the wires connecting the case buttons to the motherboard haven't come loose and that the switches still work.

    In any case, if you're sure it's the PSU you could probably get it repaired under warranty. Do you have any spares to confirm the diagnosis with? They don't need to be high power units just to start up a motherboard.
     
  12. Kierax

    Kierax What's a Dremel?

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    I don't have ANY other psu's sadly, nor anyone local enough to nab one from.


    With my motherboard normally once it recieves power the red L.E.D comes on and a digital display comes on, I am not seeing either of those?


    The psu is out of warranty sadly so if it is that then a new one is my only option.
     
  13. hitman012

    hitman012 Minimodder

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    Do those displays normally come on once you turn on the mains to the PSU? If you're not seeing those then yeah, it's most likely to be the power supply.

    As for replacements, any PSUs from Corsair, Seasonic, Antec, Tagan or Enermax are generally a safe buy.
     
  14. Burnout21

    Burnout21 Is the daddy!

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    be a man and jump start it by shorting the green and black, considering everything would be unplugged anyway, there is no harm to hardware.

    grab some old wire strip the insulation off both ends to make the contacts and bam there you have the jump start wire. check youtube for some videos and you'll soon notice there is no harm doing it.

    what motherboard you got? sounds an odd question but it might gives us a better idea.
     
  15. chrisb2e9

    chrisb2e9 Dont do that...

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    I have to agree, if you go and buy a new psu and the computer still doesn't work then you wasted your money. Take a wire or a paperclip and use it to connect the two leads in the fasion that was explained in an above post.
    Worst case scenario is that nothing happens and it is dead. second worst case scenario is that it turns on and now you have to find out what the real problem is.
     
  16. Kierax

    Kierax What's a Dremel?

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    My motherboard is the Abit IP35 Pro, well within warranty.

    As said before I don't feel fine risking a shock ;) the psu is over a year old and has run gaming computers 24/7 all of it's life.

    PSU is a Seasonic S12 600.
     
  17. chrisb2e9

    chrisb2e9 Dont do that...

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    there wont be a shock, its not like sticking a fork into an electrical socket.
    the purple pin is only 5 volts. licking a 9 volt battery would hurt more.
    like I said before, do you really want to buy a new psu and then find out its something else that is causing the problem?
     
  18. hitman012

    hitman012 Minimodder

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    The maximum possible voltage present at the DC side of an ATX power supply is only 24V, and the pin you need to short is only held at 5. You'd be subjected to more risk changing your car battery than you would performing this test.

    Power supplies are only really dangerous if you open them up and start mucking about with the internals, which is where the high voltages are. Otherwise they're pretty safe.
     
  19. Kierax

    Kierax What's a Dremel?

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    Well I tried it, and it did not spin up... to be honest I didnt even feel a thing, more like it was not even plugged in * it was * I've ordered a Corsair HX620 to replace it, which I was going to order since it's modular and has good reviews.

    Just hope nothing else is damaged inside the pc :S
     
  20. chrisb2e9

    chrisb2e9 Dont do that...

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    Glad to see you tested it, know we know that the psu was actually dead. I'm sure that the rest of the pc will be fine. I had a psu blow a cap once and my pc was fine after that.
     

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