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    Samsung U60J620DAF Power and Backlights blink

    I have this 60" Samsung that is 18 months old. When plugged in to AC, the red power led on the front of the TV AND the backlights flash in sync with each other once every second or so. This will happen indefinitely until AC is removed. I have unplugged the main board from the Power Supply and symptoms repeat as before. I have enclosed a few pictures to start, but will take more later as it is dark outside. Thank you.
    Attached Files

    #2
    Re: Samsung U60J620DAF Power and Backlights blink

    With everything connected see if STD-BY5V is constant or pulsating, also.

    Comment


      #3
      Re: Samsung U60J620DAF Power and Backlights blink

      do you see any picture during that flashing spell? What I mean is if the mainboard runs and just the backlights flash?

      Comment


        #4
        Re: Samsung U60J620DAF Power and Backlights blink

        Andrew F. Ali - Expected to see STB-5V by the connector shown in the upper center of the attached photo, but did find this SB:8V on the power supply board. If it is somehow related, I got 3-5 VDC fluctuating wildly. It didn't match the beat of the power led and backlights but maybe my meter isn't fast enough.

        Mr. CapLeaker - when plugging in to AC and seeing that flashing spell, I saw nothing that resembled picture. But with LEDs disconnected from PS and plugging in to AC, the power LED behaved normally and by turning on and hitting source on the remote, me and my flaslight were able to see the source menus at the top of the screen. The set powered down by itself shortly thereafter.
        Attached Files

        Comment


          #5
          Re: Samsung U60J620DAF Power and Backlights blink

          SB:8V is the stand by voltage. I do think you have a LED Backlights problem Do you have any experience at all in disassembly of the Panel and removing the fragile glass screen??

          Comment


            #6
            Re: Samsung U60J620DAF Power and Backlights blink

            Yes, I have done a few, but only up to 46". I guess handling the glass that big and finding a place to put it is probably the hardest part? Any words of wisdom are welcomed.

            Comment


              #7
              Re: Samsung U60J620DAF Power and Backlights blink

              A 60 incher is a big job. You would have to get a buddy to help you with this one. I use six (6) suction pads/cups. Three (3) at the top and three (3) at the bottom. Using long wooden broom handles, pass them through three (3) of the suction pads/cups handles and secure them with masking tape at the top and do the same again for the three (3) of the suction pads/cups at the bottom. Then from opposite sides lift together and rest it down on a carpeted floor covered with a bed sheet. This works for me. Luckily I don't get much 60 or 70 inchers to repair.

              Comment


                #8
                Re: Samsung U60J620DAF Power and Backlights blink

                Sounds like a good plan. How big, I guess diameter are these suction cups? What are they normally used for to help me find them?

                Comment


                  #9
                  Re: Samsung U60J620DAF Power and Backlights blink

                  The ones I have are 4-6" in diameter. They are used for lifting sheets of glass. Try e-bay as that is where I got mine from.
                  What voltages are you seeing on the Backlight LED + and - pins with the black DMM probe on the chassis GND.
                  Last edited by Andrew F. Ali; 10-02-2018, 12:36 PM.

                  Comment


                    #10
                    Re: Samsung U60J620DAF Power and Backlights blink

                    Thanks. I will check there.

                    Comment


                      #11
                      Re: Samsung U60J620DAF Power and Backlights blink

                      What voltages are you seeing on the Backlight LED + and - pins with the black DMM probe on the chassis GND.

                      Comment


                        #12
                        Re: Samsung U60J620DAF Power and Backlights blink

                        Thanks for the reply. I am currently away from the TV but will report back after I get home.

                        Comment


                          #13
                          Re: Samsung U60J620DAF Power and Backlights blink

                          Turn the backlights waaay down and see if it kinds of remedies the problem.

                          Comment


                            #14
                            Re: Samsung U60J620DAF Power and Backlights blink

                            Not exactly sure what I am looking for here, but all I can give you are values with the AC plugged in. With the LEDs disconnected from the PS, the TV will power up with remote but not for very long. So plugging in with the LEDs connected gives D+ =160 VDC. With the LEDs disconnected gives D+ =420 VDC. Both when LEDs are connected and disconnected, D- fluctuates around so much I can't really come up with good readings. Let me know if I am not giving you what you need and I can try again.

                            Comment


                              #15
                              Re: Samsung U60J620DAF Power and Backlights blink

                              Lift one leg of the diode D9001C or remove it off the board and then check the RESISTANCE in both directions of that diode, report the resistance reading, make sure that you do not touch the probe tips with your hand because I want to make sure it is not showing your body's resistance.
                              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 U60J620DAF Power and Backlights blink

                                Originally posted by MEB View Post
                                Not exactly sure what I am looking for here, but all I can give you are values with the AC plugged in. With the LEDs disconnected from the PS, the TV will power up with remote but not for very long. So plugging in with the LEDs connected gives D+ =160 VDC. With the LEDs disconnected gives D+ =420 VDC. Both when LEDs are connected and disconnected, D- fluctuates around so much I can't really come up with good readings. Let me know if I am not giving you what you need and I can try again.
                                Yes. So far you are doing an excellent job.

                                Comment


                                  #17
                                  Re: Samsung U60J620DAF Power and Backlights blink

                                  Thanks budm, always a pleasure.

                                  Black lead on Cathode - 235.2K ohms
                                  Black on Anode - 0 ohms

                                  Appears to be SF28G. Thanks.

                                  Comment


                                    #18
                                    Re: Samsung U60J620DAF Power and Backlights blink

                                    Originally posted by MEB View Post
                                    Thanks budm, always a pleasure.

                                    Black lead on Cathode - 235.2K ohms
                                    Black on Anode - 0 ohms

                                    Appears to be SF28G. Thanks.
                                    OK, that reading does not make sense if it show 0 Ohms in one of the reading and 235K in another. Are you testing by putting the probes on each end of the diode?
                                    I think you may have the same diode failure like in this thread with the same diode P/N.
                                    https://www.badcaps.net/forum/showth...t=72153&page=2
                                    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


                                      #19
                                      Re: Samsung U60J620DAF Power and Backlights blink

                                      Yes, I repeated the test several times. Digi-Key and Mouser both have the SF28G or would you recommend trying to upgrade? Any suggestions?
                                      Attached Files

                                      Comment


                                        #20
                                        Re: Samsung U60J620DAF Power and Backlights blink

                                        I would get a couple of them for either place then, and when you mount it on the board keep the legs long so the body will be 1/4 ~ 1/2 '' above the board to help cooling the diode.
                                        https://www.badcaps.net/forum/showth...t=72153&page=2 the diode did fix the problem on that OP board.
                                        I ask Jason to see if he can ship the extra one to you.
                                        Last edited by budm; 10-04-2018, 09:22 AM.
                                        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

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