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Samsung UN70KU6300F tv troubleshooting

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    Samsung UN70KU6300F tv troubleshooting

    Hi everyone. Yes, another Samsung question. Sorry for those of you that have seen your fair share.

    Background: I wanted another project to take some free time up and was looking in the free section of the local internet and saw a posting that said “free tv. Won't turn on.” I went to pick it up and at that point is when I got the word that there was a lightning strike close to the house and it hasn't worked since. At that point I really didn't want the tv but after making the trip and having the guy help me load it in the back of the truck I felt I should just drag it home.

    The tv came in the original box with original packaging and appears it was very well taken care of. Now to try to fix it. I've done as much troubleshooting as I can from the internet and now I'm kind of stuck. I don't want to just start throwing parts at it as that can get out of hand quickly.

    The tv is a Samsung UN70KU6300F. No picture

    What I've checked so far:

    When plugged in the standby light continuously flashes. Some troubleshooting I saw they were asking how many flashes. This just flashes constantly.

    The fuse on the power board is good. The strange thing is at the power connection on the board I read 121 volts. On the fuse I read 66 volts when using the chassis of the tv or a mounting hole which are electrically the same. One of the videos I watched said the mounting hole was an acceptable ground. Not sure if that's correct or where els to put my ground. Not sure why I'm coming up almost half on such a short run from the receptacle to the fuse.

    I disconnected the ribbon cable from the power board to the control board I guess it's called and the backlighting flashes at about a 1 second rate with an audible “relay” sound. I'm not an expert on these or any tv as this is the first one I've tangled with. From what I can tell, all of the backlights seem to flash.

    The last thing I've done is go to the output of the power board and measured at the pins using the diagram on the board. Multiple pins are supposed to have 13v, some 0, and some another value. I do not come up with anything close to 13. Most are 0 and the only ones that have voltage fluctuate what looks like between 2.5 and 4.5 volts but fast fluctuations.

    My first thought is that the power board probably has a problem due to the voltages on the output. I see nothing that looks like it got hot or disfigured.

    What I'm wondering about is the backlighting flashing in the one second interval. I know a lightning strike can cause all kinds of issues. Could the power board cause the flashing issue or am I possibly looking at multiple boards?

    I am far from an expert so here I am. Is there anything else I can check? I have a multimeter but no o'scope.

    I thought about taking the power board off to get a look at the other side of it but it's the lug style and even after watching a video on removing it I had no luck and quit before I destroyed something.

    Thanks in advance for any advice.
    Attached Files
    Last edited by SMDFlea; 09-08-2023, 05:42 AM. Reason: Samsung UN70KU6300F

    #2
    Re: Another Samsung tv troubleshooting

    What type of multimeter do you have, auto ranging, or a manual one, where you set the ohms, like 200, 2000, 20k etc?

    Comment


      #3
      Re: Another Samsung tv troubleshooting

      Auto-ranging

      Comment


        #4
        Re: Samsung UN70KU6300F tv troubleshooting

        Put make and model number in thread title ! ! ! https://www.badcaps.net/forum/showthread.php?t=24661
        .
        All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

        Comment


          #5
          Re: Samsung UN70KU6300F tv troubleshooting

          Thanks for getting that

          Comment


            #6
            Re: Samsung UN70KU6300F tv troubleshooting

            Maybe do a few simple measurements in ohm mode, fuse should be about 000, VX801s should show a reading maybe .5 m ohms or more, NT801S should be 000.

            Comment


              #7
              Re: Samsung UN70KU6300F tv troubleshooting

              Thanks, I'll check those measurements later today. If I can't find anything I may throw a couple of boards at it then give up. Is there any way to make sure the backlighting works in this condition or is it hard to check?

              Thinking maybe a power board and then maybe the control/main board. It took a spike with the storm I guess but without seeing any visible damage I'm just guessing at this point.

              Comment


                #8
                Re: Samsung UN70KU6300F tv troubleshooting

                Thinking that a spike would damage the powerboard or mainboard and probably not get all the way to the backlights.

                Comment


                  #9
                  Re: Samsung UN70KU6300F tv troubleshooting

                  VX801S reads 1.42m
                  NT801S reads 7.2 ohms
                  Fuse reads 0

                  Comment


                    #10
                    Re: Samsung UN70KU6300F tv troubleshooting

                    I've had a few lightning strike TVs. Sometimes it was main board, sometimes it was power board. Gotta check the power board first, and it sounds like it's bad. If your voltages are off, then you need one that's correct. Take the power board fully out the TV. Plug it in and test it. The voltages that say 13v will read 13v (or because nothing is connected possibly 8-10 steady volts--samsung sometimes labels the board with a voltage with no load-look for it). If those are good, check the jumpers for the backlights. Those should all be a steady voltage as well. I can't read the board from the picture but usually a label tells you voltages. You shouldn't even look at main board or lights until you confirm all those voltages are correct.

                    Since you have 2.5 or 5 volts at 13v pins your power board is bad. But, confirm those voltages with everything disconnected.

                    You can check backlights with LED tester, but I don't think you need to because power board voltages are bad. Get new power supply lol.

                    After you get a correct power board then you can diagnose the main board and lights if necessary.

                    Comment


                      #11
                      Re: Samsung UN70KU6300F tv troubleshooting

                      Also to remove the board, in your picture on the top left it says "lock" you have to lift the board up just slightly above that metal half sphere and pull the board down, at least in this picture it's down. Sometimes a little hard to do, so lightly tap with hammer in middle of board and it'll pop off.

                      Comment


                        #12
                        Re: Samsung UN70KU6300F tv troubleshooting

                        I was really tempted to tap that board with my rubber mallet because it acted like it was stuck but I was afraid to do it because my luck always end up busting something.

                        One more question before I order a power supply. The black plastic connector that you connect the power cord to on the board. It has two holes in the bottom next to the board where I am able to measure the voltage and it shows 122 V. The fuse is extremely close to that but using one of the mounting holes as a ground only shows half that voltage coming off the back of the fuse. Is there a ground I can use that’s on the board to maybe get a more accurate reading? I just don’t see how I can have half of a voltage loss at the fuse.
                        Last edited by Kel65; 09-11-2023, 07:41 AM.

                        Comment


                          #13
                          Re: Samsung UN70KU6300F tv troubleshooting

                          Does it really matter? The power board is bad. All kinds of random happens when things are bad. Lol just order the board

                          Comment


                            #14
                            Re: Samsung UN70KU6300F tv troubleshooting

                            You're measuring it wrong. On the hot side use the negative of the main capacitor as the ground when measuring the voltage.

                            Comment


                              #15
                              Re: Samsung UN70KU6300F tv troubleshooting

                              Post a good clear picture of the legend/map of CM875 it's right there by it, or list the pin names and expected voltages.

                              Comment


                                #16
                                Re: Samsung UN70KU6300F tv troubleshooting

                                Don't forget to check all the diodes and resistors on the top side of the board, basic test that should always be done when wondering about the power board.

                                Comment


                                  #17
                                  Re: Samsung UN70KU6300F tv troubleshooting

                                  Thanks for all of the reply's. Now I have a list of things to check. Wife has had me furniture shopping the last 3 days and hoping to finish up tomorrow then start taking measurements again.

                                  Comment


                                    #18
                                    Re: Samsung UN70KU6300F tv troubleshooting

                                    Picture of CM875

                                    Also pic of the lug. I have tapped against this sob with hammer and block of wood while lifting the edge of the board high enough to clear the lock. It does not budge. I'm hitting it the opposite direction of the solid black arrow, not the one pointing at the lock. I suppose this is the wrong direction.
                                    Attached Files

                                    Comment


                                      #19
                                      Re: Samsung UN70KU6300F tv troubleshooting

                                      Is it this type: https://www.youtube.com/watch?v=g0ojfT2rJtQ

                                      Comment


                                        #20
                                        Re: Samsung UN70KU6300F tv troubleshooting

                                        Another there, make sure you remove the screws holding where the power plug goes into the board if there is one, see how he does it there: https://www.youtube.com/watch?v=uOr8rLj_rTk
                                        Last edited by nomoresonys; 09-13-2023, 05:55 PM.

                                        Comment

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