DPS285BP 5v standby transformer blown

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  • Hounddoghill
    New Member
    • Feb 2022
    • 6
    • usa

    #1

    DPS285BP 5v standby transformer blown

    Sharp TV LC-80LE633U
    Power supply board DPS 285BP Run TKB096WJQZ

    Standby transformer markings (attached picture)
    MP-130I(01)
    AV-DP11153 Delta
    Dcum 1244(03) H6P

    So an event in the primary exploded the cap (C7901)on pin one of the Standby circuit IC. So after replacing a couple diodes a the 2.2ohm resistor(fuse) I found the transformer inputs are open.

    Anyone know about replacements for this transformer?
    I suspect the original is not available.
    https://www.badcaps.net/forum/images/smilies/silly.gif




    Attached Files
  • R_J
    Badcaps Legend
    • Jun 2012
    • 9535
    • Canada

    #2
    Re: DPS285BP 5v standby transformer blown

    Which pins are you checking on the transformer?

    Comment

    • Hounddoghill
      New Member
      • Feb 2022
      • 6
      • usa

      #3
      Re: DPS285BP 5v standby transformer blown

      1-2 and 3-4 are both open
      5-7 Output still has .1 ohm (6 and 6 windings in parallel)

      there is a suggested transformer spec on the data sheet for standby power IC.

      1-2 is 72 windings
      2-4 is less don't recall

      Pretty sure it's dead

      Comment

      • R_J
        Badcaps Legend
        • Jun 2012
        • 9535
        • Canada

        #4
        Re: DPS285BP 5v standby transformer blown

        That's not the configuration, the primary is 2~3, The vcc feedback is 1~4 Pins 5~7 are the secondary.

        Also check R7907, and I would also replace C7907 and C7918
        Attached Files
        Last edited by R_J; 02-04-2022, 04:40 PM.

        Comment

        • Hounddoghill
          New Member
          • Feb 2022
          • 6
          • usa

          #5
          Re: DPS285BP 5v standby transformer blown

          good info

          2-3 is 2.8 ohm
          1-4 is open

          should 1-4 be open?

          Comment

          • R_J
            Badcaps Legend
            • Jun 2012
            • 9535
            • Canada

            #6
            Re: DPS285BP 5v standby transformer blown

            No 1~4 should not be open. Check the transformer leg to see if the wire is broken, and also make sure you are making a good connection with your probes

            Comment

            • Hounddoghill
              New Member
              • Feb 2022
              • 6
              • usa

              #7
              Re: DPS285BP 5v standby transformer blown

              Checked again and 1-4 open and bobbin wires look solid at pins.

              So I think I need a replacement plan.

              Comment

              • Hounddoghill
                New Member
                • Feb 2022
                • 6
                • usa

                #8
                Re: DPS285BP 5v standby transformer blown

                I used my digital microscope and the coil at pin one is burnt.
                Second photo is good side.

                Anyone ever take one of these part and rewind?
                I am going to try and open.

                Or know of a a replacement


                Attached Files

                Comment

                • daltonjr.
                  Member
                  • Jul 2016
                  • 45
                  • Austria

                  #9
                  Re: DPS285BP 5v standby transformer blown

                  I have exact same transformer from Grundig Tv that is shorted. Have you fixed it, found replacement one or some alternative... ? Thanks!

                  Comment

                  • daltonjr.
                    Member
                    • Jul 2016
                    • 45
                    • Austria

                    #10
                    Re: DPS285BP 5v standby transformer blown

                    Does anyone know if the two pins on secondary are ment to be shorted / 0 resistance, or that indicates a faulty transformer?

                    Comment

                    • R_J
                      Badcaps Legend
                      • Jun 2012
                      • 9535
                      • Canada

                      #11
                      Re: DPS285BP 5v standby transformer blown

                      You are measuring the DC resistance of the winding, basically a piece of wire, it will check shorted or less than 1Ω

                      Comment

                      • Clifton11283
                        Member
                        • Aug 2022
                        • 10
                        • Malta

                        #12
                        Re: DPS285BP 5v standby transformer blown

                        I have a similar issue on a DPS-162KP-1A power supply board on a sharp TV. I found fuse F7001, resistor R7900, capacitor C7901, IC7903 blown. Cannot find any further faulty components but when I test the TV with a serial bulb circuit to check for short circuits, the bulb is lighting which means I still have a short circuit somewhere. Any help what can I check further please?

                        Comment

                        • algutria
                          New Member
                          • Oct 2023
                          • 2
                          • USA

                          #13
                          Re: DPS285BP 5v standby transformer blown

                          5-7 shall be about 16 ohms in a good transformer.
                          What I did is to buy a power cards for parts in e-bay for 25 dollars. that include the transformer.
                          Usually when transformer T7901 is shorted 0.0 to 0.2 between terminals 5-7 blows the cap C7817 (1nF) or the input resistor R7900 (2.2 Ohms)

                          Comment

                          • algutria
                            New Member
                            • Oct 2023
                            • 2
                            • USA

                            #14
                            Re: DPS285BP 5v standby transformer blown

                            Originally posted by daltonjr.
                            Does anyone know if the two pins on secondary are ment to be shorted / 0 resistance, or that indicates a faulty transformer?
                            It is shorted. Shall be around 16 Ohms in a good transformer terminals 5-7

                            Comment

                            • R_J
                              Badcaps Legend
                              • Jun 2012
                              • 9535
                              • Canada

                              #15
                              Re: DPS285BP 5v standby transformer blown

                              The secondary winding is small and the DC resistance of the wire will be close to 0Ω

                              Comment

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