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power supply faulty

Discussion in 'Troubleshooting and Repair' started by Marius Ghita, Dec 22, 2014.

  1. Marius Ghita

    Marius Ghita

    6
    0
    Dec 22, 2014
    Hi guys I need your help please

    I have a power supply faulty and I am trying to fix it, but I need some advice. My main power capacitors are fried , but I can't find the capacitors , are really hard to find , can I use a lower capacitance or higher?
    The capacitors that are fried are primary side:
    1600uf 250v dc
    can I replace it with 1500uf 250v dc or 1800uf 250vdc
    please let me know if you have any ideas.

    Thanks Marius
     
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Hi Marius and welcome to Electronics Point :)

    Are you sure they're 1600 µF? They would be pretty big! Can you show us a photo?
     
  3. Marius Ghita

    Marius Ghita

    6
    0
    Dec 22, 2014
    Hi

    this is the cap x2
    80mm circumference
    45mm hight
    it's a atx power supply 1050w
    the value of the caps reads around 750uf
     

    Attached Files:

    Last edited: Dec 22, 2014
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Yeah, I think the 1600 µF marking is a lie. At that size, even 750 µF is a lot.

    Why do you think they're "fried"?
     
  5. Marius Ghita

    Marius Ghita

    6
    0
    Dec 22, 2014
    Because I have other capacitors that are biger than this once and the value reading quite close.
    The 10.000uf 50v reads 10.060uf ok
    the 470uf 200v reads 473uf ok
    but this once should read close to 1600uf so this is how I came to the conclusion that this is the culprit of the fault.
    Hopefully someone can help me .

    Thanks Marius
     
  6. Marius Ghita

    Marius Ghita

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    0
    Dec 22, 2014
    So you think that the 1500uf should do the job?
     
  7. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    You would normally expect the measured capacitance to be close to the printed value, but with components from certain countries, you can't necessarily believe the numbers.

    If both of them measure 750 µF the power supply will still work. And mains filter capacitors don't fail very often. It's much more common for the output filter capacitors to fail.

    What is the fault with the power supply?
     
  8. Marius Ghita

    Marius Ghita

    6
    0
    Dec 22, 2014
    It's not starting even if I short the green and black. I've checked all the caps on the primary side and diodes and all the mosfet, now the interesting part comes in the short happened at one of the primary mosfets because I can see the marks on pcb but it reads ok the only component i can't measures is the 8 pins chip
     
  9. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,266
    Nov 28, 2011
  10. Marius Ghita

    Marius Ghita

    6
    0
    Dec 22, 2014
    Hi krisbluenz
    I have tried to make some pictures but I get home late and there isn't natural light to make them that good like in tutorial. I will do it after Christmas when I'm off.

    Thanks
     
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