Uni-t UTP3315TFL-II stuck at 40V laboratory power supply

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  • marce002
    Badcaps Veteran
    • May 2018
    • 316
    • Argentine
    #1

    Uni-t UTP3315TFL-II stuck at 40V laboratory power supply

    Hello

    My 2 years old unit is showing and outputing around 44.33v , values are real comparing with my tester... current seems to be fine if could be tested passing CC to CV as usual, rotating knov volt does not change values at all.... always arround 44 vol,

    PLEASE

    what to test?? in the pictures i have checked
    all is clean at 100%!! not blown components or traces of exploded caps or anything... most diodes are ok and transistors too i think..caps are good shape















    Attached Files
    Last edited by marce002; 07-22-2022, 12:42 PM.
    Marcelo J
    Tags: None
    • stj
      Great Sage 齊天大聖
      • Dec 2009
      • 30934
      • Albion
      #2
      Re: Uni-t UTP3315TFL-II stuck at 40V laboratory power supply

      resolder all the front panel pots - they have hardly any solder on them!!

        Comment

        • marce002
          Badcaps Veteran
          • May 2018
          • 316
          • Argentine
          #3
          Re: Uni-t UTP3315TFL-II stuck at 40V laboratory power supply

          revised and they are almost perfect soldered...
          Marcelo J

            Comment

            • marce002
              Badcaps Veteran
              • May 2018
              • 316
              • Argentine
              #4
              Re: Uni-t UTP3315TFL-II stuck at 40V laboratory power supply

              it started to work fine again by itself, maybe the relay stucked or similar due to its sounds...tks for your help, and if you can confirm that a relay might have affected to generate this issue you are welcome..
              Marcelo J

                Comment

                • redwire
                  Badcaps Legend
                  • Dec 2010
                  • 3900
                  • Canada
                  #5
                  Re: Uni-t UTP3315TFL-II stuck at 40V laboratory power supply

                  A stuck relay is not the problem, that does not cause the output voltage to get stuck high.
                  I see many bad solder joints on the larger through-hole parts. Spend some time and resolder all of them.
                  Some pretty dodgy parts used, this Vreg IC (pic) seems to have been found on the road in china and put to use.

                  You can hit the unit with your hand, or tap the boards with a pen and see if a bad connection still exists. Because the fault will blow up whatever is connected to the power supply... it makes sense to actually troubleshoot and fix it before it kills something.
                  Attached Files

                    Comment

                    • spiros.p
                      Senior Member
                      • Dec 2020
                      • 89
                      • Greece
                      #6
                      Re: Uni-t UTP3315TFL-II stuck at 40V laboratory power supply

                      agree with bad solder.i have cheap axiomet linear psu and was full of bad joints out from the box..to92 transistor bad soldered and not triger the relay.booth of them i have two.resolder booth chance all the c(r)apacitors and is working properly.

                        Comment

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