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ID parts & troubleshoot a short - UN75F6300AF Samsung TV

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    ID parts & troubleshoot a short - UN75F6300AF Samsung TV

    Hello!

    I have a Samsung 75" UN75F6300AF TV. This thread shows good photos of the various parts, I'll post my photos of my issues which are:
    1) Identify what this 'yellow nub' is on the back side of my power supply circuit board. Is it important? where do I get a replacement?
    2) find a source / replacement part for this 15D050 thermistor.
    3) What is this little black chip? does it look ok? how do I test it/replace it?
    4) how else would I troubleshoot a short in the board?


    Back story:
    Months ago, an LED strip seemed to have gone bad (took a while to understand what the issue was). Then one evening, the TV was on, working fine and then "Pop, Pop, POP! zap" the TV went off. Took out the power supply (BN44-00621C) and discovered an obvious capacitor had blown.

    I figured out a good replacement for that, soldered it, and now the fuse keeps blowing, i.e. a short somewhere (replacement fuse is the correct rating and time-delay type). I have visually inspected the board in more detail and discovered a little nub on the back side of the board was also popped off at the solder joint. I am pretty sure it was popped off when I first had the issue. I've included photos of 'good ones' on the back of the board. There are four in total (SP1, SP2, SP3, SP4). SP3 is the one that was popped off. It is located under the TS801CS transformer(?) roughly where the red dot is, but on the other side of the board.

    I also noticed later on that the WTR 15D050 thermistor is cracked. Personally I think this may have happened later on e.g. after I swapped out the fuse twice. I think if this was there from the beginning, I would have seen the crack. Where can I buy these? can't seem to find an identical replacement (green, etc) and want to be sure I get the correct one.

    The only other thing that visually looked weird was this "chip". Again, on the back side of the circuit board. I have no clue what it is or how to test it. Markings seem to say "YC" and "312". I say it's weird because the solder looks rough, like it was melted and refroze.

    So once I replace these/test these, anything else I should do to test for shorts. I've already bought a new power supply and TV is working again. Also testing was done with just the power supply, so I'm pretty certain the short is in the power supply board.
    Attached Files
    Last edited by my-name-is-john; 01-22-2021, 01:36 PM. Reason: adding photos, typos.

    #2
    Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

    even if i succeed to remove the short and make this board working.. i will never never install it again on the TV LOL... keep it as parts for the coming days..

    Comment


      #3
      Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

      LOL agreed. After the initial capacitor replacement didn't work, I gave up and ordered a new board. It's just eating at me that it's not working though, so I have to figure it out...

      Comment


        #4
        Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

        Take a look inside the connector on the power supply that goes to the main board and look for any signs of arcing. The pins will look burned. If so replace both the power supply and that cable also. We service a sports bar with alot of these and we have found this problem on 3 of them already.
        Attached Files

        Comment


          #5
          Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

          Thanks Bruce! I'll check the cables when I take apart the TV to replace the LED strip that went bad (should have parts in two weeks). I didn't see any signs of arching on the power supply side of the connector though.

          Comment


            #6
            Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

            When the cap CP814 shorted, did you check the mosfet it is across? I would check all fets in that area. Although NT801s is cracked it is likely still working, check its resistance.
            Last edited by R_J; 01-26-2021, 01:04 PM.

            Comment


              #7
              Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

              Originally posted by R_J View Post
              Although NT801s is cracked it is likely still working, check its resistance.
              Data sheet for NT801, looks like it should be 5 ohms cold
              Attached Files

              Comment


                #8
                Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

                Originally posted by RDC55 View Post
                Data sheet for NT801, looks like it should be 5 ohms cold
                Thanks, I am measuring about 12 Ohms over the thermistor. what does that mean?

                Comment


                  #9
                  Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

                  Originally posted by R_J View Post
                  When the cap CP814 shorted, did you check the mosfet it is across? I would check all fets in that area. Although NT801s is cracked it is likely still working, check its resistance.
                  First, Thanks for all the suggestions!

                  So, no MOSFET "nearby", the capacitor was near a rectifier (18NM60N, https://cdn.badcaps-static.com/pdfs/...c3b4fa564d.pdf). I'm measuring 6Mohm on one side, and infinity on the other...does that indicate a bad diode rectifier?

                  I've also found four MOSFETs near the 'top' of the board. FFPF20UA60DN is stamped on them. I think this is their datasheet: https://cdn.badcaps-static.com/pdfs/...7967ef1ee7.pdf

                  I've never tested MOSFETs before, so, following a you tube video, I 'discharge' the gate with my finger. I put the ground (black) on the center post, and 'positive' on the right post. In the discharged state I get a reading of ~.524 (not really "open", it always goes to that value). When I charge the gate with the positive and then re-read drain to source, the value has now dropped to ~0.112. what does that mean? I've done this with two MOSFETs and have gotten similar results. Am I doing it right? photos attached of my setup.

                  EDIT TO ADD: I've found two MOSFETS near the blown CAP 26NM60N. they're on the HOT side of the board. I'll check those tomorrow.
                  Attached Files
                  Last edited by my-name-is-john; 02-04-2021, 03:46 PM.

                  Comment


                    #10
                    Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

                    Originally posted by R_J View Post
                    When the cap CP814 shorted, did you check the mosfet it is across? I would check all fets in that area. Although NT801s is cracked it is likely still working, check its resistance.
                    Tested the two MOSFETs near the blown capacitor (26NM60N) and one of them is showing continuity (multimeter beeps) across all three pins. I think this one's bad! Thanks R_J for the suggestion!

                    Comment


                      #11
                      Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

                      Does anyone know what this "SP4" component is? I still haven't been able to figure it out.
                      Attached Files

                      Comment


                        #12
                        Re: ID parts & troubleshoot a short - UN75F6300AF Samsung TV

                        Originally posted by brucetv View Post
                        Take a look inside the connector on the power supply that goes to the main board and look for any signs of arcing. The pins will look burned. If so replace both the power supply and that cable also. We service a sports bar with alot of these and we have found this problem on 3 of them already.
                        Bruce, took apart my TV last weekend to replace the bad LED strip (full story at link below... spoiler: I was successful ). I didn't see any indications of arching on any connectors. I will say when plugged in the TV to see the LEDs that were out (three rows) some of the bad rows had LEDs that were dimly lighting up intermittently (e.g. low voltage?). I really think the issue with having the LED row out for so long caused my power supply to eventually fail, but that's just my theory.

                        https://www.badcaps.net/forum/showth...t=51061&page=3

                        Comment

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