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Does this transformer look bad? Photo attached

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    Does this transformer look bad? Photo attached

    This is a transformer on a subwoofer plate amplifier. I see what appears to be resin all over it. Appears almost like it has heated and leaked out or it could be from manufacturing?. The amplifier keeps blowing fuses. I did identify a blown Mosfet but I am also questioning the state of this transformer. Any insight please? Thank you!
    Attached Files

    #2
    Re: Does this transformer look bad? Photo attached

    The transformer is normal, it is just varnish to stop the transformer from creating annoying audible oscillation noises.

    The yellow glue though might very well be your problem, see attached photos.
    It becomes conductive with age, known problem for 20 or 30 years.
    Ask the manufacturer why they keep using it...
    Attached Files
    "The one who says it cannot be done should never interrupt the one who is doing it."

    Comment


      #3
      Re: Does this transformer look bad? Photo attached

      This yellow / brown glue, remove on sight. It either causing you trouble or going to cause trouble.

      Comment


        #4
        Re: Does this transformer look bad? Photo attached

        Originally posted by mitsu2k View Post
        This is a transformer on a subwoofer plate amplifier. I see what appears to be resin all over it. Appears almost like it has heated and leaked out or it could be from manufacturing?. The amplifier keeps blowing fuses. I did identify a blown Mosfet but I am also questioning the state of this transformer. Any insight please? Thank you!
        Can you please show a picture of the complete circuit board
        9 PC LCD Monitor
        6 LCD Flat Screen TV
        30 Desk Top Switching Power Supply
        10 Battery Charger Switching Power Supply for Power Tool
        6 18v Lithium Battery Power Boards for Tool Battery Packs
        1 XBox 360 Switching Power Supply and M Board
        25 Servo Drives 220/460 3 Phase
        6 De-soldering Station Switching Power Supply 1 Power Supply
        1 Dell Mother Board
        15 Computer Power Supply
        1 HP Printer Supply & Control Board * lighting finished it *


        These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

        1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
        2 Hem Saw Computer Stack Board

        All of these had CAPs POOF
        All of the mosfet that are taken out by bad caps

        Comment


          #5
          Re: Does this transformer look bad? Photo attached

          Originally posted by sam_sam_sam View Post
          Can you please show a picture of the complete circuit board
          Here is a picture of the complete board but I have already removed the caps and the mosfets. I found two of the 47uf 50v caps to have high ESR (One 8ohms and the other 33ohms). The other caps were within spec but I am replacing them all anyway. I scraped off the glue in the areas where it appeared to be making a bridge between two or more points. What I noticed is the glue was only conductive where heat had turned it a dark brown. It was easy to flake off where it had darkened but a real pain where it's a lighter color. I thought I would just leave those areas but cut out the areas that bridged other component legs or traces.
          Attached Files
          Last edited by mitsu2k; 01-08-2023, 04:51 PM.

          Comment


            #6
            Re: Does this transformer look bad? Photo attached

            it's not just conductive, it's corrosive and can eat through wires!

            Comment


              #7
              Re: Does this transformer look bad? Photo attached

              Originally posted by stj View Post
              it's not just conductive, it's corrosive and can eat through wires!
              Thank you, do you know of a trick to easily remove it? Also would replacing it with hot glue melt be acceptable to keep components from vibrating loose?

              Comment


                #8
                Re: Does this transformer look bad? Photo attached

                you dont need to replace it,
                as for removing it, some people say IPA will loosen it - i just go at it with small longnose pliers and a flat screwdriver!

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