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    Samsung led strips not working

    Was watching tv 3 weeks ago and screen went black, but sound continued to work. Called Square trade and they walked me through some test steps. They concluded that it was the power board(BN44-00775A) and came out and replaced it. Tv worked fine for19 days until one night I turned it toward the dinner table. It went black again, but still had sound.

    Called SquareTrade again, and they said it could not be repaired. They are replacing it with what they say is a comparable tv, but I hate to just throw this one away

    Search the internet and came across this site. Read a thread by vergezee and it sounded like we had the same problem. Thought I would post the readings you ask him for and see if you could help me.

    On plug to main board
    Pin1 A13v=13v
    Pin3 A13v=13v
    Pin5 A13v=13v
    Pin7 A13v=13 v
    Pin9CND
    Pin2 UD=2.34v
    Pin4 PWM_BLU=3.33v
    Pin6 Ps_ON=3.94v
    Pin8 GDN
    Pin10 GDN

    On plug to led strips
    D- 570v
    D- 571v
    NC
    S+ 407v

    NC
    S- 407v
    NC
    D+ 426v
    D+ 426v

    Could this be a bad connection to the led strips or bad strips themselves?

    #2
    Re: Samsung led strips not working

    Are those LED Voltage reading done with ref to chassis Gnd?
    Will not be surprise if you have open circuit in the LED string.
    Never stop learning
    Basic LCD TV and Monitor troubleshooting guides.
    http://www.badcaps.net/forum/showthr...956#post305956

    Voltage Regulator (LDO) testing:
    http://www.badcaps.net/forum/showthr...999#post300999

    Inverter testing using old CFL:
    http://www.badcaps.net/forum/showthr...er+testing+cfl

    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
    http://s807.photobucket.com/user/budm/library/

    TV Factory reset codes listing:
    http://www.badcaps.net/forum/showthread.php?t=24809

    Comment


      #3
      Re: Samsung led strips not working

      Yes, grounded black lead to chassis and red to each pin on back of plug.

      Comment


        #4
        Re: Samsung led strips not working

        Shopjimmy says your TV is a UN60H or UN60J

        Very difficult to remove the panel on a 60" TV without cracking it to get at the strips even with experience.

        https://www.shopjimmy.com/samsung-bn...upply-unit.htm

        From shopjimmy -
        " PLEASE NOTE: The LED strips (part number BN96-29074A/BN96-29075A) in the models listed are prone to failure. If this board does not fix the problem with your TV, it is likely that you have defective LED strips. Power supply and LED strips failures cause similar symptoms in these models. "

        Comment


          #5
          Re: Samsung led strips not working

          On plug to led strips
          D- 570v
          D- 571v
          NC
          S+ 407v

          NC
          S- 407v
          NC
          D+ 426v
          D+ 426v


          Are you sure you did not label those pins wrongs? D+ is the Anode of the LED string that is fed by the LED driver Voltage so no way you can have D - pin which is the Cathode return of the LED string to have higher Voltage reading than the D+.
          So far it points to open circuit in the LED string, I.E. wires, connectors, LED, etc.
          Never stop learning
          Basic LCD TV and Monitor troubleshooting guides.
          http://www.badcaps.net/forum/showthr...956#post305956

          Voltage Regulator (LDO) testing:
          http://www.badcaps.net/forum/showthr...999#post300999

          Inverter testing using old CFL:
          http://www.badcaps.net/forum/showthr...er+testing+cfl

          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
          http://s807.photobucket.com/user/budm/library/

          TV Factory reset codes listing:
          http://www.badcaps.net/forum/showthread.php?t=24809

          Comment


            #6
            Re: Samsung led strips not working

            Thought I had it right. I will double check it to make sure.

            Comment


              #7
              Re: Samsung led strips not working

              Got different readings this time. Don't know why.
              D- 318
              D- 318
              Nc
              S+ 381
              Nc
              S- 381
              Nc
              D+ 426
              D+ 426
              This is reading left to right looking at the board or back side of the plug

              Comment


                #8
                Re: Samsung led strips not working

                OK, lift up one leg of the Diode D9001C and then check the resistance in both direction of that diode.
                Picture provided by shopjimmy.
                Attached Files
                Never stop learning
                Basic LCD TV and Monitor troubleshooting guides.
                http://www.badcaps.net/forum/showthr...956#post305956

                Voltage Regulator (LDO) testing:
                http://www.badcaps.net/forum/showthr...999#post300999

                Inverter testing using old CFL:
                http://www.badcaps.net/forum/showthr...er+testing+cfl

                Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                http://s807.photobucket.com/user/budm/library/

                TV Factory reset codes listing:
                http://www.badcaps.net/forum/showthread.php?t=24809

                Comment


                  #9
                  Re: Samsung led strips not working

                  I have a cheap multimeter so I set it to ohms and I got .6 one way and .7 the other.

                  Comment


                    #10
                    Re: Samsung led strips not working

                    You need to test in resistance mode, we are looking for resistance leakage of the diode.
                    BTW, you need to lift one leg of the diode off the board to do the test.
                    Is the Diode Diode is SF28G?
                    If the diode has leakage resistance then that will explain why you have 426V on the Anode and 318 On the Cathode of the LED string, it also means the Vdrops on the LED string is only 426V-318V = 108V!
                    BTW, you should invest in LED tester: https://www.shopjimmy.com/sid-gj2c-l...ght-tester.htm
                    Last edited by budm; 11-04-2018, 06:49 PM.
                    Never stop learning
                    Basic LCD TV and Monitor troubleshooting guides.
                    http://www.badcaps.net/forum/showthr...956#post305956

                    Voltage Regulator (LDO) testing:
                    http://www.badcaps.net/forum/showthr...999#post300999

                    Inverter testing using old CFL:
                    http://www.badcaps.net/forum/showthr...er+testing+cfl

                    Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                    http://s807.photobucket.com/user/budm/library/

                    TV Factory reset codes listing:
                    http://www.badcaps.net/forum/showthread.php?t=24809

                    Comment


                      #11
                      Re: Samsung led strips not working

                      Sorry my meter does not have a resistance setting that I see. I have detached one leg from the board. Maybe I need to read more on how to check for resistance.

                      Comment


                        #12
                        Re: Samsung led strips not working

                        "I have a cheap multimeter so I set it to ohms and I got .6 one way and .7 the other."
                        If that is what you are getting with one leg of the diode is lifted off the board then that diode is bad.
                        Never stop learning
                        Basic LCD TV and Monitor troubleshooting guides.
                        http://www.badcaps.net/forum/showthr...956#post305956

                        Voltage Regulator (LDO) testing:
                        http://www.badcaps.net/forum/showthr...999#post300999

                        Inverter testing using old CFL:
                        http://www.badcaps.net/forum/showthr...er+testing+cfl

                        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                        http://s807.photobucket.com/user/budm/library/

                        TV Factory reset codes listing:
                        http://www.badcaps.net/forum/showthread.php?t=24809

                        Comment


                          #13
                          Re: Samsung led strips not working

                          If I set the ohms to 200 I get.6 and .7. If I set it to 2000 I get 1 both ways. I can get a diode tomorrow and replace it. What diode number do I look for.

                          Comment


                            #14
                            Re: Samsung led strips not working

                            I found the manual on this multimeter and It does have a diode resistance setting on it. The results were the same though. It fluctuated between .9 and 1 in both directions. So this means the diode is bad? Thanks for your patience with me and for trying to help me.

                            Comment


                              #15
                              Re: Samsung led strips not working

                              "1" may mean over range.
                              Retest in Diode mode again and see if it still show conduction in both directions, if it does then that diode is bad.
                              What kind of meter is it?
                              Never stop learning
                              Basic LCD TV and Monitor troubleshooting guides.
                              http://www.badcaps.net/forum/showthr...956#post305956

                              Voltage Regulator (LDO) testing:
                              http://www.badcaps.net/forum/showthr...999#post300999

                              Inverter testing using old CFL:
                              http://www.badcaps.net/forum/showthr...er+testing+cfl

                              Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                              http://s807.photobucket.com/user/budm/library/

                              TV Factory reset codes listing:
                              http://www.badcaps.net/forum/showthread.php?t=24809

                              Comment


                                #16
                                Re: Samsung led strips not working

                                have you unsoldered and lifted one side of the diode as budm suggests sometimes other things in circuit can give false readings

                                Comment


                                  #17
                                  Re: Samsung led strips not working

                                  Yes , I took one leg loose from the board and I get the same readings in both directions. As I said all I have is a cheap Harbour Freight multimeter. Really I have two of the same meters and they read the same. I will try to get a better meter later today if I have time. May need to just order a new board.

                                  Comment


                                    #18
                                    Re: Samsung led strips not working

                                    ok sound like you just have a bad diode can you get one locally and swap it out

                                    Comment


                                      #19
                                      Re: Samsung led strips not working

                                      Just got home. How do I tell what range of diode to buy? I don't see any markings on the bad one.

                                      Comment


                                        #20
                                        Re: Samsung led strips not working

                                        the diode should have some sort of markings on it look on post 8 and zoom into that diode you can see some writing in white you may need a magnifier too check the writing on your part
                                        Attached Files
                                        Last edited by vinceroger69; 11-05-2018, 09:58 AM.

                                        Comment

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