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Need help ID'ing a diode - T2D85

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    Need help ID'ing a diode - T2D85

    Hi all -

    I have a TV SMPS with a bad diode.

    The marking around the component body is "T2D85" but i haven't been able to find a datasheet for it.

    The diode is a through hole axial. The body is black. The band and text is a dark red color.


    Edit: I have a replacement part for U101 coming next week from Digi-Key.
    Attached Files
    -Thomas
    I'm a hardware engineer focused on networking equipment for my day job. I void warranties and fix consumer electronics for fun.

    #2
    Re: Need help ID'ing a diode - T2D85

    What is wrong with the diode? It can be a TVS diode and they can check open. If it is checking shorted in circuit it could be due to the shorted ic
    Last edited by R_J; 03-15-2020, 02:49 PM.

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      #3
      Re: Need help ID'ing a diode - T2D85

      I removed it to check for shorts in the supply circuit for U101. While i had it out, I noticed that the diode doesn't beep with the meter in diode mode - no forward drop.
      -Thomas
      I'm a hardware engineer focused on networking equipment for my day job. I void warranties and fix consumer electronics for fun.

      Comment


        #4
        Re: Need help ID'ing a diode - T2D85

        I find the root part number for T2 diode is ST02D as a Shindengen "trankiller" TVS zener+diode inside. So a T2D85 is 85V ST02D-85 and would test open-circuit unless you can test it past 85V.

        I don't think it's a rectifier diode but would have to see the schematic.

        Comment


          #5
          Re: Need help ID'ing a diode - T2D85

          Originally posted by redwire View Post
          I find the root part number for T2 diode is ST02D as a Shindengen "trankiller" TVS zener+diode inside. So a T2D85 is 85V ST02D-85 and would test open-circuit unless you can test it past 85V.

          I don't think it's a rectifier diode but would have to see the schematic.

          Thanks for the lead! I'll look into the PN you identified.
          -Thomas
          I'm a hardware engineer focused on networking equipment for my day job. I void warranties and fix consumer electronics for fun.

          Comment


            #6
            Re: Need help ID'ing a diode - T2D85

            check the symbol underneath it

            Comment


              #7
              Re: Need help ID'ing a diode - T2D85

              Originally posted by ngth82 View Post
              I removed it to check for shorts in the supply circuit for U101. While i had it out, I noticed that the diode doesn't beep with the meter in diode mode - no forward drop.
              These type of diodes don't "BEEP", they are usually two internal diodes with common cathode
              Attached Files
              Last edited by R_J; 03-15-2020, 03:57 PM.

              Comment


                #8
                Re: Need help ID'ing a diode - T2D85

                Thanks guys. The board symbol for this component is the same as the one immediately south of the red box from the pic in Post #1.

                I just realized that i didn't post the board number information.

                This is a LGIT SMPS board for a Philips TV. Board PCB PN: 2300KEG031A-F

                Funny, Coppell TV Repair also mentions that U101 is a common failure (which this appears to be the case):LINK
                Attached Files
                Last edited by ngth82; 03-15-2020, 04:27 PM.
                -Thomas
                I'm a hardware engineer focused on networking equipment for my day job. I void warranties and fix consumer electronics for fun.

                Comment


                  #9
                  Re: Need help ID'ing a diode - T2D85

                  I think OP's could be a ST02D-82 (note datasheet wrong 67V spec). Mouser sells them.

                  It looks like other people mistakenly think these T2D snubber diodes "power clampers" are open-circuit, when they are just HV zener plus diode:
                  looking for T2D80 https://www.badcaps.net/forum/showth...t=20211&page=2
                  Sony Diode T2D98 ST02D-140 https://www.badcaps.net/forum/showth...t=54016&page=2
                  T2D98 https://www.badcaps.net/forum/showthread.php?p=671655
                  T2D40 https://www.badcaps.net/forum/showth...067#post221067

                  Comment


                    #10
                    Re: Need help ID'ing a diode - T2D85

                    Also, looks like this component sits across the two terminals of the transformer that bridges the hot and cold side of the SMPS. I removed the transformer and checked for shorts across the three separate windings. The transformer to be okay.
                    -Thomas
                    I'm a hardware engineer focused on networking equipment for my day job. I void warranties and fix consumer electronics for fun.

                    Comment


                      #11
                      Re: Need help ID'ing a diode - T2D85

                      That TVS (HV zener) diode (D106A) is across the primary, In some cases they use a UF4007 for D106 and have C103 and R102 populated which are in series with the uf4007 fast recover diode.
                      Last edited by R_J; 03-15-2020, 06:00 PM.

                      Comment


                        #12
                        Re: Need help ID'ing a diode - T2D85

                        Update: The FSQ510 arrived and was replaced on the SMPS.

                        The TV fires up and appears to work.
                        Attached Files
                        -Thomas
                        I'm a hardware engineer focused on networking equipment for my day job. I void warranties and fix consumer electronics for fun.

                        Comment

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