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    Samsung UN65KS9800FXZA Help

    Hi all. I recently purchased a broken Samsung UN65KS9800FXZA. The TV would turn on and off with the status light making the appropriate changes. However, the screen was black, no backlights activated, and there was no sound. When the seller sold it to me, he stated that there was sound. He also stated that the problem occurred when he was updating his PlayStation. The screen just went black.

    When disconnecting the cable from the LED driver board, the backlights would turn on. With the backlights on, I checked all positive voltages for the LED connectors and they all read fine. I don't believe that the LED's are faulty.

    I checked all voltages on the connectors, referencing the service manual and boards, and all were correct with the exception of the TCON board. I ordered a used board from eBay, installed it, and powered the device. The blue indicator on the TCON board flashed a few times and no change on the symptoms. I was never able to get the blue light to activate again. I checked for continuity on the one fuse, on the TCON, and it was ok.
    Looking at all of the boards, I do not see any visible damage, discoloration, or burning. There were also no audible sounds when the second TCON failed, just the flashing light.

    I went ahead and ordered a new main board and power supply from eBay. After installation, I got sound but still no picture or backlights. The indicator LED on the TCON would still not light up.

    After reading some other posts, I learned that a faulty tab bonding board or faulty panel could be the culprit and I'm now hesitant to install another replacement TCON before troubleshooting that board. I pulled off the protective cover, and closely inspected the capacitors and ribbons connecting the board to the panel. They all look the same, and don't show any visible indicators of a short or damage. Additionally, the tabs appear to be properly bonded to the board. Is it possible that a faulty main board or power supply could be the root cause of a failed TCON, or is that type of failure solely caused by components downstream (tab bonding board/panel)?

    I can post pictures of whatever would be useful. Also, I have watched the posted video about checking the capacitors on the tab bonding board. I can obtain those readings if necessary. It may take a day or so due to the sheer number of them on the boards.

    Thanks in advance! Also, if it would be useful to anyone, send me a message and I can share the repair manual.

    #2
    Re: Samsung UN65KS9800FXZA Help

    When the backlights came on when cable was unplugged most likely means backlights and powerboard are ok, so probably issue with mainboard or panel or a cable or connection on that side. Have a look inside the connector cable on the powerboard side see if there's any dark or burnt looking discoloration, doubtful tho if all the voltages are correct. Do the one ribbon cable at a time from tcon to panel test, make sure tv is UNPLUGGED from power during any cable disconnecting or re-connecting, unhook one side plug power in turn on, you should get a good picture on the half that's still connected, if only one half is good then probably a panel problem.

    Comment


      #3
      Re: Samsung UN65KS9800FXZA Help

      Going through all of the tests again in the service manual. The service manual is stating that all 5 fuses on the LD board should have 30v. I have two LD boards and both have the same fuse reading 12.8v. Could the service manual be wrong?

      Comment


        #4
        Re: Samsung UN65KS9800FXZA Help

        Originally posted by Bdig View Post
        Going through all of the tests again in the service manual. The service manual is stating that all 5 fuses on the LD board should have 30v. I have two LD boards and both have the same fuse reading 12.8v. Could the service manual be wrong?
        Can you provide the service manual you are using?
        Upload pictures of the whole backside of the TV showing all the boards will also help.
        Last edited by budm; 03-28-2020, 05:03 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


          #5
          Re: Samsung UN65KS9800FXZA Help

          When you checked the voltage on th LD fuses, were the backlights on? If not, remove the cable that gave you the backlights in the first post and check again.

          Comment


            #6
            Re: Samsung UN65KS9800FXZA Help

            Correct, same reading with backlights on and off. To clarify, the backlights turn on with the cable connecting the LD to the TCON and main removed.

            Photos and manual to follow shortly...

            Comment


              #7
              Re: Samsung UN65KS9800FXZA Help

              Manual that I'm using. Check the troubleshooting PDF.
              Attached Files

              Comment


                #8
                Re: Samsung UN65KS9800FXZA Help

                See attached photos. I've included an additional photo of the LED showing which fuse is low.
                Attached Files
                Last edited by Bdig; 03-28-2020, 07:16 PM.

                Comment


                  #9
                  Re: Samsung UN65KS9800FXZA Help

                  From what I can tell looking at the led arrays at SJ, each line of leds has 10 led's so if each led is 3v, the drive voltage should be 30v. but you say you have the backlights on with only 12v? If you do, I doubt they are very bright.
                  B13 volts is the supply from the power supply board, but I suspect the voltage gets boosted on the LD board to 30V

                  Comment


                    #10
                    Re: Samsung UN65KS9800FXZA Help

                    The lights seem pretty bright. What are the odds that I got a used LD board with the same malfunction? It is used, but the website said it was checked for proper function. Also, the replacement TCON that I installed is fried. I haven't been able to get the LED to flash again since the first 5 seconds after I plugged the TV in.

                    Comment


                      #11
                      Re: Samsung UN65KS9800FXZA Help

                      Originally posted by Bdig View Post
                      The lights seem pretty bright. What are the odds that I got a used LD board with the same malfunction? It is used, but the website said it was checked for proper function. Also, the replacement TCON that I installed is fried. I haven't been able to get the LED to flash again since the first 5 seconds after I plugged the TV in.
                      In post number 2, it was suggested that you do the "one cable at a time disconnected between the tcon and panel"... did you ever attempt this test?
                      Based on your statement quoted above / here, it is likely your problem is related to the panel.

                      Comment


                        #12
                        Re: Samsung UN65KS9800FXZA Help

                        Not yet. I have a replacement TCON arriving tomorrow. The last one lasted a few seconds. I never got a picture or backlights in those few seconds. Will update with the results.

                        Comment


                          #13
                          Re: Samsung UN65KS9800FXZA Help

                          :-( do not put in the new tcon card until you check / determined what is "fried" on the old one.

                          Comment


                            #14
                            Re: Samsung UN65KS9800FXZA Help

                            Unfortunately we are seeing more and more panel problems in the 8000 and 9000 series than the 5000 6000 and 7000 series. For what you pay for these high end SUHD Samsung's you shouldn't see panel problems in some cases within 2 years of ownership. I usually steer my customers towards the 7000 series without the stupid One Connect boxes and the picture still looks good. Much lower repair costs later on too. A real disappointment Samsung. In their quest for a zillion nits their panel technology is falling short. Can you imagine your 2 year old 8K Samsung panel shorting out?

                            Comment


                              #15
                              Re: Samsung UN65KS9800FXZA Help

                              Alright, the anticipation was killing me and 50/50 odds seemed pretty good lol. I put in the new TCON and had the left ribbon connected. Everything started up good and I have a picture on the left side. I'm not going to hook up the right side until I get a bit more advice. The black area on the left side is a bit noisy. See attached pic. Is noise caused by bad caps on the tab bonding board?
                              Attached Files

                              Comment


                                #16
                                Re: Samsung UN65KS9800FXZA Help

                                ok... some "gambled progress".... do not connect the other side. I didn't read the whole thread but does this set have tabs on each side and along the bottom?

                                Comment


                                  #17
                                  Re: Samsung UN65KS9800FXZA Help

                                  Tabs along the bottom only

                                  Comment


                                    #18
                                    Re: Samsung UN65KS9800FXZA Help

                                    Maybe try "tape cutoff" method, example there: https://www.youtube.com/watch?v=7TT8QYeN1s8

                                    Comment


                                      #19
                                      Re: Samsung UN65KS9800FXZA Help

                                      Found this video https://youtu.be/srccct1mDIU. Followed his method and isolated the short to the blue tab bonding board. Looking at the rear, it's the one on the far left. With all other ribbons connected, minus the one going to that board, I have 3/4 picture on the display. I'll start work on isolating the bad component in the next few days and keep y'all posted.

                                      Comment


                                        #20
                                        Re: Samsung UN65KS9800FXZA Help

                                        good work.... hopefully you can save the set with a minor component fix. But beware that potentially the problem may lie in the side "in panel drivers" which can't be repaired... that is what the "tape cutoff" method gets around.

                                        Comment

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