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PSU only supplies 5VSB. Doesn't turn on.

Discussion in 'System Builder's Advice' started by TRWOV, Nov 30, 2012.

  1. TRWOV

    TRWOV

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    So I got a mini ITX case but the included 150w PSU doesn't turn on. I hooked up a PSU tester and it shows an active 5VSB but it doesn't turn on even with the paper clip method.

    I opened the PSU as I suspected that maybe the green (PWROK?) cable was unsoldered or something but it's soldered fine.

    The issue is that the store doesn't have it in stock anymore so it can't replace it and the PSU is custom, almost like a FTFX PSU but shorter (FTFX is 65x85x14 this one is 65x65x14).



    I already contacted the manufacturer to see if I could get the PSU replaced and I could return the case and get a refund but I wanted to check with you guys first. Any ideas? Googled a lot of things but didn't find anything useful.
     
    Crunching for Team TPU
  2. brandonwh64

    brandonwh64 Addicted to Bacon and StarCrunches!!!

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    To resolve alot of headache I would personally just return and get another case of your choosing. These PSU's that come with cases are usually bottom of the barrel and hope they work out of the box.
     
    Crunching for Team TPU
  3. McSteel

    McSteel

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    The secondary doesn't start. Having a working 5VSB means your primary side (APFC if any, Bridge Rectifier, primary switchers) also works. Your problem could be in the primary transformer, in one or more of the secondary switchers, or in the secondary filtering and regulation stage (regulation and filter coils, filter caps). There could also be a short somewhere (possibly a long component lead touching the PSU casing). In any case, it's probably the secondary control/protections IC that's shutting off the PSU to prevent damage.

    Could you post some photos of the inside of your PSU? Also, do you have access to a soldering iron, digital multimeter, spare parts (coils, capacitors)?
     
  4. TRWOV

    TRWOV

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    I took the PSU out of the casing and it still doesn't turn on. I think that there's a short somewhere as it turned on when I was trying to unplug it and touched the bottom of the PCB by accident; gave me a little shock and the fan started to spin but it was over as soon as I pulled my hand. I'm having a look at the PCB but can't identify any broken trace or bridging going on.

    I have a soldering iron and some caps but no transformer or coils. I'll take some pics.
     
    Crunching for Team TPU
  5. McSteel

    McSteel

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    Is it the FSP PSU from the CM Elite 100 case? If not, can you identify it's topology (guessing double forward + group regulation), and are you able to check for continuity if not exact resistance values? Can you borrow or buy a digital multimeter? Is it even worth it to you?
     

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