brand new buck converter does not step up or down

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  • bohaboha
    Badcaps Veteran
    • Nov 2012
    • 973
    • sweden

    #1

    brand new buck converter does not step up or down

    To test I plug in a 12v source and try by plugging a multimeter on the output and turning on the blue trim potentiometer it's fix at 12v however I turn it up or down what could be wrong ?
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  • sam_sam_sam
    Badcaps Legend
    • Jul 2011
    • 6037
    • USA

    #2
    Re: brand new buck converter does not step up or down

    Are you sure that you are turning the pot control for the voltage because one is voltage and the or one is current

    Comment

    • R_J
      Badcaps Legend
      • Jun 2012
      • 9535
      • Canada

      #3
      Re: brand new buck converter does not step up or down

      You don't have a load, so it likely just charged the output cap to the highest voltage.

      Comment

      • bohaboha
        Badcaps Veteran
        • Nov 2012
        • 973
        • sweden

        #4
        Re: brand new buck converter does not step up or down

        Originally posted by sam_sam_sam
        Are you sure that you are turning the pot control for the voltage because one is voltage and the or one is current
        to be sure I tried both but I know that the left trim is for volts if viewed from above

        Comment

        • bohaboha
          Badcaps Veteran
          • Nov 2012
          • 973
          • sweden

          #5
          Re: brand new buck converter does not step up or down

          Originally posted by R_J
          You don't have a load, so it likely just charged the output cap to the highest voltage.
          do you need load to test? if so can you explain further please

          Comment

          • sam_sam_sam
            Badcaps Legend
            • Jul 2011
            • 6037
            • USA

            #6
            Re: brand new buck converter does not step up or down

            Probably for best results because this is a buck converter not a boost converter which as adjustable the voltage control your voltage would go beyond the input voltage but on a buck converter it is the opposite in that you have to have some load on it for the voltage control to work but the current control also affects the voltage output
            Last edited by sam_sam_sam; 08-30-2022, 07:54 PM.

            Comment

            • bohaboha
              Badcaps Veteran
              • Nov 2012
              • 973
              • sweden

              #7
              Re: brand new buck converter does not step up or down

              Originally posted by R_J
              You don't have a load, so it likely just charged the output cap to the highest voltage.
              please look at this from minit 12 https://www.youtube.com/watch?v=9--_jaxiXhE&t=16s

              Comment

              • sam_sam_sam
                Badcaps Legend
                • Jul 2011
                • 6037
                • USA

                #8
                Re: brand new buck converter does not step up or down

                What happens when you put a load on the output dose it charge at all

                Comment

                • bohaboha
                  Badcaps Veteran
                  • Nov 2012
                  • 973
                  • sweden

                  #9
                  Re: brand new buck converter does not step up or down

                  Originally posted by sam_sam_sam
                  What happens when you put a load on the output dose it charge at all
                  have not tried yet, but I will do and get back to you. normally you should be able to test even without load

                  Comment

                  • stj
                    Great Sage 齊天大聖
                    • Dec 2009
                    • 30991
                    • Albion

                    #10
                    Re: brand new buck converter does not step up or down

                    no, because the output cap holds a charge, and the charge is going into the chips feedback pin.
                    unless your output cap(s) have a discharge resistor you never power up without a load

                    Comment

                    • bohaboha
                      Badcaps Veteran
                      • Nov 2012
                      • 973
                      • sweden

                      #11
                      Re: brand new buck converter does not step up or down

                      Originally posted by stj
                      no, because the output cap holds a charge, and the charge is going into the chips feedback pin.
                      unless your output cap(s) have a discharge resistor you never power up without a load
                      Clear and concise explanation thank you

                      Comment

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