Samsung QN55Q80R Bad Panel Help

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  • Diah
    Badcaps Legend
    • Feb 2013
    • 6355
    • Germany

    #21
    Re: Samsung QN55Q80R Bad Panel Help

    how many pins you masked now LOL.. could you count on which pin masked right now.. seem you have one of gamma under mask.

    Comment

    • Davi.p
      Hobbist Tech
      • Sep 2009
      • 4289
      • Italy - Milan

      #22
      Re: Samsung QN55Q80R Bad Panel Help

      That whiteish picture sounds to me as you have bad vcom signal, maybe you covered that pin but it is mandatory to have it on to the panel, check vcom test point on the panel

      Comment

      • Storyteller12
        Badcaps Veteran
        • Jun 2020
        • 624
        • USA

        #23
        Re: Samsung QN55Q80R Bad Panel Help

        Originally posted by Diah
        how many pins you masked now LOL.. could you count on which pin masked right now.. seem you have one of gamma under mask.
        Pins 19 or 20-26. It's hard to count those tiny pins.

        Comment

        • Storyteller12
          Badcaps Veteran
          • Jun 2020
          • 624
          • USA

          #24
          Re: Samsung QN55Q80R Bad Panel Help

          Originally posted by Davi.p
          That whiteish picture sounds to me as you have bad vcom signal, maybe you covered that pin but it is mandatory to have it on to the panel, check vcom test point on the panel
          Vcom is pins 6,7,8 and those are not covered.

          Comment

          • Davi.p
            Hobbist Tech
            • Sep 2009
            • 4289
            • Italy - Milan

            #25
            Re: Samsung QN55Q80R Bad Panel Help

            havdd is there? try to change tape type with the thinner thing you have, usually kapton is quite thin

            Comment

            • Diah
              Badcaps Legend
              • Feb 2013
              • 6355
              • Germany

              #26
              Re: Samsung QN55Q80R Bad Panel Help

              Originally posted by Storyteller12
              Pins 19 or 20-26. It's hard to count those tiny pins.
              if this count correct and the pin chart of lotas correct then you have just masked half of the SPI... in this case i will remove the mask and just remove the spi carefully

              Comment

              • howardc64
                Badcaps Veteran
                • Jun 2017
                • 580
                • United States

                #27
                Re: Samsung QN55Q80R Bad Panel Help

                Lots of transposed pictures and easily confusing. Judging from the pics in post #9 and #13, OP masked

                CN1301 (I'm assuming pic is CN1301 since thats the half thats not working) pin 74-82 (can't tell from pic if mask was continuous across this range). Service manual ( closely related, likely correct CN1301 pin out. link p112 for main board pic, p129 for CN_1301 )



                This is LC_VGP1_GOA, STVP1_GOA, CKVB1-4_GOA, CKV2-4_GOA

                Maybe should just try to mask out the 8 gate driver pins on the bad side (CKVB1-4 and CKV1-4) per post #14 (but I think post had wrong pinout diagram : CN1300 rather than CN1301) Probably can skip CKV1_GOA for total of 7 pins since short isn't there from current test. If that works, then gradually tried fewer CKVB1-4 CKV2-4..

                BTW, for precise experimental masking. I do it this way. Mark off 12 pin steps (service manual pin listing is in rows of 4) on the connector. Cut thin white paper precisely. Paper don't move when inserting the flex into the connector.

                Attached Files
                Last edited by howardc64; 05-09-2023, 05:21 PM.

                Comment

                • Storyteller12
                  Badcaps Veteran
                  • Jun 2020
                  • 624
                  • USA

                  #28
                  Re: Samsung QN55Q80R Bad Panel Help

                  Sorry was sick for a few days and didn’t have a chance to troubleshoot.

                  So, I removed SPI (25q80dvsig) chip and removed all the tape masking pins On lvds cable. Tv turn on and stays on but no image. Its not rebooting like it was. But if i unplug the side with the bad lvds cable i no longer get an image on half the screen like I did before. So I’m assuming in need the spi chip for it to produce an image.

                  Would a new spi chip fix the issue?

                  Comment

                  • lotas
                    Badcaps Legend
                    • Jan 2016
                    • 4540
                    • Russia

                    #29
                    Re: Samsung QN55Q80R Bad Panel Help

                    Why remove 25q80dvsig, it belongs to T-CON and it contains all your panel settings! Without it, T-CON will not work.

                    Comment

                    • Storyteller12
                      Badcaps Veteran
                      • Jun 2020
                      • 624
                      • USA

                      #30
                      Re: Samsung QN55Q80R Bad Panel Help

                      I tried doing the other winbond chip (25q40) as suggested by diah but the standby light didn’t come on and couldn’t power the tv on.

                      I just figured I would try this chip and see what happens.

                      Not really sure what to try honestly. I think this one is headed for the dump.

                      Any other suggestions?

                      Comment

                      • lotas
                        Badcaps Legend
                        • Jan 2016
                        • 4540
                        • Russia

                        #31
                        Re: Samsung QN55Q80R Bad Panel Help

                        It was rather about this SPI 25Q32.
                        Attached Files

                        Comment

                        • Storyteller12
                          Badcaps Veteran
                          • Jun 2020
                          • 624
                          • USA

                          #32
                          Re: Samsung QN55Q80R Bad Panel Help

                          Lol. My bad, I didn’t know.

                          Thanks for pointing out the obvious.

                          Comment

                          • Storyteller12
                            Badcaps Veteran
                            • Jun 2020
                            • 624
                            • USA

                            #33
                            Re: Samsung QN55Q80R Bad Panel Help

                            Ok, replaced the eeprom and removed the spi on buffer board and tv reboots like it originally did. I tape off pins again with spi removed and same washed out image.

                            Comment

                            • lotas
                              Badcaps Legend
                              • Jan 2016
                              • 4540
                              • Russia

                              #34
                              Re: Samsung QN55Q80R Bad Panel Help

                              Also check the TVS Diodes on the strips with a multimeter for low resistance or short circuit.
                              Attached Files

                              Comment

                              • Davi.p
                                Hobbist Tech
                                • Sep 2009
                                • 4289
                                • Italy - Milan

                                #35
                                Re: Samsung QN55Q80R Bad Panel Help

                                have you tested vcom on the panel boards? It must be around 7,5v. Or maybe is something about bad vgh/vgl, low value.. test those plus avdd
                                Last edited by Davi.p; 05-15-2023, 02:09 PM.

                                Comment

                                • Storyteller12
                                  Badcaps Veteran
                                  • Jun 2020
                                  • 624
                                  • USA

                                  #36
                                  Re: Samsung QN55Q80R Bad Panel Help

                                  Originally posted by Davi.p
                                  have you tested vcom on the panel boards? It must be around 7,5v. Or maybe is something about bad vgh/vgl, low value.. test those plus avdd
                                  Sorry, I'm not a tech so you have to point me in the right direction where vcom, vgh,vhl are to measure them. I don't see anything labeled with them, but my eyes are the greatest either and the print is small.

                                  Thanks

                                  Comment

                                  • Davi.p
                                    Hobbist Tech
                                    • Sep 2009
                                    • 4289
                                    • Italy - Milan

                                    #37
                                    Re: Samsung QN55Q80R Bad Panel Help

                                    the test points are probably on the panel's boards, search them with mgnifier or post sectional photos

                                    Comment

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