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Thread: Looking to repair a PSU

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    Default Looking to repair a PSU

    Greetings! Long time reader. Great site, the in depth reviews were very helpful and I bought my new PSU based on them (EVGA 750 G2).

    Being replaced is a SilverStone ST60F I bought in 2006. I had to RMA once, but for nearly 8 years its been reliable and trouble free besides one fan replacement.



    In January the computer shut down and didn't want to start back up for a moment. It eventually did, and having experienced this before in another machine, I figured bad PSU, which was the case as I've had no problems since switching it out.

    That said, this would be a great backup PSU or one for another machine if I could get it fixed. Yesterday I opened it up and looked around.







    Bingo.

    Only one I saw that looked bad. I'd like to replace it and get this going again.

    I freely admit I'm no expert with electronics. I've replaced a micros witch on my Performance Mouse MX and blown capacitors on my old LCD monitor, however I had the luxury of finding a cap kit for the model and didn't have to go hunting capacitors down.

    If looks like this Teapo capacitor is 2200uF 6.3V rated at 105°C (says SC105°C on the cap).

    Would this be the correct replacement?

    http://www.ebay.com/itm/141507047875

    Thanks.

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    sith'ari (04-07-2016)

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    Although lot of people here are PSU experts, for this particular issue (cap replacement), i believe that the most suitable person to guide you would be Pavel / Behemot (he is replacing caps all the time), but recently he got banned from Jonnyguru.com (*sometimes he just can't control his mouth!!), so you could contact him through his site, Hardwareinsights.com ( http://www.hardwareinsights.com/wp/ )
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    1. No KZG is not the right replacment. And they are not that reliable.

    2. According to your statement of the PSU failure, it seems that it is NOT the caps but something else.
    So it may be a waste of time to replace the caps.


    3. What kind of equipment do you have?
    You should have at least a good soldering Iron as well as quality solderwick.

    But still, I think replacing the caps will be a waste because something else may have failed.

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    With Stefan, KZG isn't good and the PSU probably has some more problems.

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    Agreed, KZG may or may not be from a reliable batch but isn't a suitable replacement. Go with KZE or KY if you insist on NCC, though I'd rather recommend Panasonic FM or FR for instance.

    With that said, it looks like a 5VSB issue to me, rather than the more obvious filtering cap(s) on the secondary. Probably one of the smaller caps between the primary and secondary heatsinks is bad (those 25/35/50V caps with 50uF or less of capacitance). They're usually responsible for feedback signal decoupling, but I'd have to get a better look to be able to tell which ones are the most likely culprits.

    Those petite caps tend to dry up over time, and usually need to be replaced 1:1, because the control circuitry timing is sensitive to their exact specs, both internal resistance (ESR) and capacitance.
    Careful what you wish for... You just might get it.

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    KYB is also a decent replacement. Though ESR is rather on the low side...

    Still, with a PSU not doing anything it's very probable that something else is wrong but the main filtering caps.

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    Quote Originally Posted by Stefan Payne View Post
    Still, with a PSU not doing anything it's very probable that something else is wrong but the main filtering caps.
    The OP stated that it did power on after a while, if I understand the post correctly.

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    Thanks for the replies!

    I'm no expert on identifying capacitors, it was easy when I replaced the bad ones on my monitor because they came in a repair kit for that model.

    As far as hardware, I have a 10W and a 30W iron, solder wick, flux, and solder.

    When the computer shut down, it took a moment or two but it did power back up again. I had just gotten a 500W Cooler Master PSU as part of a hardware bundle I bought off a friend not a week prior, so to troubleshoot I swapped PSUs out and the problem never came back.

    I figured it might be worth a shot, I don't need it, just hate to throw away things that might be repairable.

    I can post some more photos later of the internals, but here it is running with that nifty jumper the EVGA came with. Fired right up, not dead yet!

    Last edited by Intrepidation; 04-07-2016 at 09:19 PM.

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    Quote Originally Posted by McSteel View Post
    Agreed, KZG may or may not be from a reliable batch but isn't a suitable replacement. Go with KZE or KY if you insist on NCC, though I'd rather recommend Panasonic FM or FR for instance.

    With that said, it looks like a 5VSB issue to me, rather than the more obvious filtering cap(s) on the secondary. Probably one of the smaller caps between the primary and secondary heatsinks is bad (those 25/35/50V caps with 50uF or less of capacitance). They're usually responsible for feedback signal decoupling, but I'd have to get a better look to be able to tell which ones are the most likely culprits.

    Those petite caps tend to dry up over time, and usually need to be replaced 1:1, because the control circuitry timing is sensitive to their exact specs, both internal resistance (ESR) and capacitance.
    Like these?

    http://www.mouser.com/ProductDetail/...8YqVotsLM6Y%3d

    Did my best to photograph all of the caps I could find. Visually at least, only the one looks bad.















    Last edited by Intrepidation; 04-07-2016 at 09:33 PM.

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    Quote Originally Posted by Intrepidation View Post
    Like these?

    http://www.mouser.com/ProductDetail/...8YqVotsLM6Y%3d

    Did my best to photograph all of the caps I could find. Visually at least, only the one looks bad.
    Yeah, like those. As I said, I personally prefer FM to FR, even though the stated (but not necessarily the actual) life expectancy is lower.

    As for the caps, those marked in red are all suspect, regardless of whether they're bulging/leaking or not:





    If the component marked in yellow is a small < 220uF cap, then it's suspicious as well. Otherwise I've mistaken something else for a cap - sorry, the images don't show it very well.

    These small caps tend to dry up, especially when near a source of heat and deprived of airflow. If you don't have an ESR meter, you might as well swap them out for equivalents in terms of specs.
    Careful what you wish for... You just might get it.

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