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    #1

    TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

    Hi all...

    I am using an old PSU for my old-server...Model is TK-920TX by Task International Inc....Detailed specs you can find here ...

    A description of what happened :

    I recently bought a Bidirectional SATA-to-PATA & PATA-to-SATA adapter to test...It is a small board powered by a 4-pin floppy connector...with the device came a 4-pin floppy to 4-pin ata molex converter...

    I connected the device using this converter, powered by the above mentioned PSU...after powering on and before getting into Windows, the cables of the converter were set on fire, so i immediately unpluged the power supply cable of the PSU to protect the machine from further damage...

    After that, the server could not power-on, so i replaced the PSU with another one and all worked fine...

    I powered on the "faulty" psu to examine it and tested the voltage of the rails with my DMM...everything seemed fine except the 12V & the -12V rails, which measured approx. ~10.7V...

    I opened the PSU for internal visual examination but i could not locate any component to have failed/burnt...

    Here are some photos :
















    If anyone can give a hint and cotribute in troubleshooting , welcome...

    If photos of specific areas are needed, i can upload more...

    Thank you in advance for your help



    felix
    Tags: None
    #2
    Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

    Replace the Fuhjyyu.
    At least all with vents but preferably all.
    Yes, they are THAT bad.
    Mann-Made Global Warming.
    - We should be more concerned about the Intellectual Climate.
    -
    Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
    - Dr Seuss
    -
    You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
    -

    Comment

      #3
      Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

      The Fuhjyyus are crap and need to be replaced, but that's probably not the problem here. Check all the secondary rectifiers on +12v and -12v rails for a shorted or open rectifier. Then check all the rectifiers on the remaining rails (+5v, -5v and +3.3v). Then trace and check the Vsense feedback path from +12v and +5v back to the controller daughter-card, in particular the resistive voltage divider network - it may have a blown resistor. If all of these look clean, then you may have a blown controller IC or op-amp on the controller daughter-card on the secondary side - it's not very clear in the photos.

      Comment

        #4
        Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

        Originally posted by felix
        connected the device using this converter, powered by the above mentioned PSU...after powering on and before getting into Windows, the cables of the converter were set on fire, so i immediately unpluged the power supply cable of the PSU to protect the machine from further damage...
        How exactly did the cables get set on fire? Did they just burn up themselves or did someone short something to cause that scenario to happen?

        But as the others have mentioned, replace the Fuhjyyu caps as they are total garbage caps.
        Don't find love, let love find you. That's why its called falling in love, because you don't force yourself to fall, you just fall. - Anonymous

        Comment

          #5
          Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

          Not worth saving
          The PSU looks like a deer design

          Just throw it away and be happier still, Corsair has a new 400w PSU for about $50, great PSU if you are not looking to spend more...
          "The one who says it cannot be done should never interrupt the one who is doing it."

          Comment

            #6
            Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

            do what linuxguru said: no need to replace fuh-crap untill you get it working.
            as it may happen you swap them all and still not get it working.

            i don't really think short-circuit on output will damage caps.

            damage was caused because psu doesn't have overcurrent protection, or it has it but it wasn't working.
            (type of the i.c. on daughterbaord should reveal that..)

            btw. can we see that pata-sata adapter?

            Comment

              #7
              Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

              What I meant was it isn't worth doing anything if you aren't going to replace the Fuhjyyu too.
              Two already look a little puffy on top. (By pair of red wires in 2nd pic.)

              I agree with Per Hansson too.
              That PSU is junk and it will cost more to fix it that it'll be worth when you are done.
              Better to just replace it.

              If you want to do it for the learning experience then that's fine.

              .
              Mann-Made Global Warming.
              - We should be more concerned about the Intellectual Climate.
              -
              Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
              - Dr Seuss
              -
              You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
              -

              Comment

                #8
                Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

                >What I meant was it isn't worth doing anything if you aren't going to replace the Fuhjyyu too.

                sure...but later.
                because it was working ok no matter the fuh.
                so yeah, he should change those, IF it gets it working, because changing fuh and not doing anything else might not solve it. ioe chances are it won't, as l.guru said.

                psu is not so good if it can't protect itself from faulty load, yeah, but that aside, this design is not too bad.
                there are surely 2 categories below this one.
                regarding that, are you sure psu u're using has oc protection?
                tried it?
                shorted 12v to ground, and it survived?

                Comment

                  #9
                  Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

                  First of all, I really appreciate your fast response of you all...

                  The Fuhjyyu will be replaced ASAP...i just made a uF-V list and tomorrow i'm gonna search for replacements....Is there any brand that i should also avoid ?


                  Originally posted by linuxguru
                  The Fuhjyyus are crap and need to be replaced, but that's probably not the problem here. Check all the secondary rectifiers on +12v and -12v rails for a shorted or open rectifier. Then check all the rectifiers on the remaining rails (+5v, -5v and +3.3v). Then trace and check the Vsense feedback path from +12v and +5v back to the controller daughter-card, in particular the resistive voltage divider network - it may have a blown resistor. If all of these look clean, then you may have a blown controller IC or op-amp on the controller daughter-card on the secondary side - it's not very clear in the photos.
                  I'll try to track that down...i have little experience from such circuits but seems like a nice "troubleshooting proejct"...

                  Originally posted by stevo1210
                  How exactly did the cables get set on fire? Did they just burn up themselves or did someone short something to cause that scenario to happen?

                  But as the others have mentioned, replace the Fuhjyyu caps as they are total garbage caps.
                  The cables just burnt up themselves a few seconds after POSTing (i think a little after the windows-loading scrolling bar appeared)..The faulty connector is already disposed (i got very mad when that happened, so i threw it in the garbage asap )...

                  Originally posted by Per Hansson
                  Not worth saving
                  The PSU looks like a deer design

                  Just throw it away and be happier still, Corsair has a new 400w PSU for about $50, great PSU if you are not looking to spend more...
                  Originally posted by PCBONEZ
                  What I meant was it isn't worth doing anything if you aren't going to replace the Fuhjyyu too.
                  Two already look a little puffy on top. (By pair of red wires in 2nd pic.)

                  I agree with Per Hansson too.
                  That PSU is junk and it will cost more to fix it that it'll be worth when you are done.
                  Better to just replace it.

                  If you want to do it for the learning experience then that's fine.

                  .
                  I couldn't agree more with both of you...Yes, the PSU is a piece of junk compared to newer,fresh designs...it's a part from an era that i didn't care much about PSU's (how wrong was i...), but it seems a good chance to get some knowledge from this project and you all...

                  Originally posted by i4004
                  do what linuxguru said: no need to replace fuh-crap untill you get it working.
                  as it may happen you swap them all and still not get it working.

                  i don't really think short-circuit on output will damage caps.

                  damage was caused because psu doesn't have overcurrent protection, or it has it but it wasn't working.
                  (type of the i.c. on daughterbaord should reveal that..)

                  btw. can we see that pata-sata adapter?
                  I will get replacement capacitors and then try to trail down what linuxguru said that might be the problem...


                  Here is a photo of the adapter :




                  Originally posted by i4004
                  >What I meant was it isn't worth doing anything if you aren't going to replace the Fuhjyyu too.

                  sure...but later.
                  because it was working ok no matter the fuh.
                  so yeah, he should change those, IF it gets it working, because changing fuh and not doing anything else might not solve it. ioe chances are it won't, as l.guru said.

                  psu is not so good if it can't protect itself from faulty load, yeah, but that aside, this design is not too bad.
                  there are surely 2 categories below this one.
                  regarding that, are you sure psu u're using has oc protection?
                  tried it?
                  shorted 12v to ground, and it survived?
                  I don't even know about OVP of this PSU...specs don't say anything about it, but afaik it has survived many power outages and/or urged shutdowns....i have it since 2001 if i remember correct...


                  The machine that supported this PSU is now supplied by a Chieftec Smart Power 350W ATX PSU ...as far as i know this is far better quality...


                  Again, thank you all for your replies...

                  Comment

                    #10
                    Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

                    get the SATA adapter replaced. It's burnt up.

                    Cheers, Wizard

                    Comment

                      #11
                      Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

                      why? he can use it as a tester for other psus, to see would they take it!
                      hehe..just kidding.

                      about protection: felix could you read what's written on the ics on the daughterboard?
                      daughterboard is hting photographed here
                      http://i256.photobucket.com/albums/h...04886_crop.jpg
                      and ics are those black rectangles with metal pins coming out of them, and connecting to printed circuit board...

                      Comment

                        #12
                        Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

                        The first one is SEC KA7500B and the second is HA17393 :



                        Comment

                          #13
                          Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

                          I agree with PC one of the Fukyuus on that daugherboard looks a bit bulged.

                          The focus isn't too good so it may be just glue though.

                          I purged all of the Fukyuus on my Antecs even the low value ones. Luckily though they weren't on the line filters too.

                          Your PWM controller is a KA7500B here is the datasheet:



                          The other 8 pin IC HA17393 is a dual comparator:

                          Last edited by Krankshaft; 10-28-2008, 10:02 PM.
                          Elements of the past and the future combining to make something not quite as good as either.

                          Comment

                            #14
                            Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

                            I got the capacitors...unfortunately, i got most from the first store and the brand is "Lelon" (anyone has info about quality?), but the second store i went (for the rest), had KY series Nippon Chemicon....I should have gotten all of them from the 2nd store....well, nevermind...

                            I 'll try to have it all installed by tomorrow, to give feedback in case you are curious about the result ...

                            Comment

                              #15
                              Re: TASK 200W ATX PSU - 10.7V on 12V rail after an "accident"?

                              Good for the learning experience I agree
                              Just a small question, are you sure 12v wasn't this low before the accident aswell?
                              Maybe the caps are dead so the rest of the circuit is overworked...

                              Anyway, replace the caps and you will see

                              Originally posted by i4004
                              regarding that, are you sure psu u're using has oc protection?
                              tried it?
                              shorted 12v to ground, and it survived?
                              Yup, a few times
                              Easy when you are modding stuff to accidentally short 5v or 12v to ground
                              Never had a PSU fail due to it, just shutdown... (And then power right back up after a power cycle)
                              "The one who says it cannot be done should never interrupt the one who is doing it."

                              Comment

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