Bad backlights suspected on Sharp LC-C5255U LCD

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  • SurrealMustard
    Badcaps Veteran
    • Jan 2015
    • 486
    • The United States of America

    #1

    Bad backlights suspected on Sharp LC-C5255U LCD

    I'm working on this Sharp 52" LCD (conventionally backlit; not LED) and it has what appears to be at least one dead backlight. It powers on briefly with a blank screen, then shuts off with a blinking green light. In the time that it is on, I can see a horizontal area that is dimmer than the rest, so I'm pretty sure that this is a bad backlight issue.

    The trouble is, I can't find replacements anywhere for this model. Is there any way to find out what kind of backlight it needs without tearing the whole thing apart? If not, is there an easy way to bypass the system and rig it up to run with one less lamp?
    Attached Files
  • dskall
    Badcaps Legend
    • Oct 2016
    • 2905
    • usa

    #2
    Re: Bad backlights suspected on Sharp LC-C5255U LCD

    You could replace with a zener, but it would be easier to just replace the led
    I assume no responsibility for any stupid suggestions I might post.

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Bad backlights suspected on Sharp LC-C5255U LCD

      What is the LCD panel number? You may be able to get the CCFL or they may be EEFL from CCFLWAREHOUSE.
      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

      • dskall
        Badcaps Legend
        • Oct 2016
        • 2905
        • usa

        #4
        Re: Bad backlights suspected on Sharp LC-C5255U LCD

        My mistake. Missed that it wasn't led. Here's a video and example of bypassing a tube. Not for your set but may work.
        https://www.youtube.com/watch?v=Dh01ZepjDp0
        Last edited by dskall; 05-22-2017, 11:48 AM.
        I assume no responsibility for any stupid suggestions I might post.

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: Bad backlights suspected on Sharp LC-C5255U LCD

          Bypassing in that Samsung or SONY only works if the lamps are driven by the Balancer circuit.
          Similar to this one.
          https://www.youtube.com/watch?v=oE6K4xBVweA
          Last edited by budm; 05-22-2017, 07:20 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

          • SurrealMustard
            Badcaps Veteran
            • Jan 2015
            • 486
            • The United States of America

            #6
            More details about this model; backlights replacement or bypass feasible?

            I finally got the rear cover off and got a look at (as well as pictures of) the layout. There are two inverter boards on the right side and none on the left. The Runtka478wjzz inverter that this model uses appears to actually be for a Sharp panel (not just a Sharp-branded television). No sticker is obviously visible identifying the exact model of the panel, so I'm not sure how to find out what kind of lamps this thing needs (the sticker might be hidden under something though, so I'll try to keep an eye out).

            If I'm reading the markings correctly, these inverters have number 2874025500 transformers on them.

            Beside lamp replacement, the other question is, is there an easy way to bypass one of these in order to allow it to continue to operate without trying to run the defective backlight?
            Attached Files

            Comment

            • dskall
              Badcaps Legend
              • Oct 2016
              • 2905
              • usa

              #7
              Re: Bad backlights suspected on Sharp LC-C5255U LCD

              It's possible one of the tubes came out of the socket and you would only have to reconnect
              I assume no responsibility for any stupid suggestions I might post.

              Comment

              • SurrealMustard
                Badcaps Veteran
                • Jan 2015
                • 486
                • The United States of America

                #8
                Socket reconnection q

                Originally posted by dskall
                It's possible one of the tubes came out of the socket and you would only have to reconnect
                By re-seating the inverter board?

                Comment

                • Andrew F. Ali
                  Badcaps Legend
                  • Jan 2014
                  • 2450
                  • Trinidad & Tobago

                  #9
                  Re: Bad backlights suspected on Sharp LC-C5255U LCD

                  If you are willing I could go through the process to convert your CCFL backlit TV to a LED backlit TV.....I am doing so currently with a LG 42in....I did it 5 times already but with 32in screens without callback.......

                  Comment

                  • attainteddragon
                    Badcaps Veteran
                    • Apr 2013
                    • 764
                    • australia

                    #10
                    Re: Bad backlights suspected on Sharp LC-C5255U LCD

                    andrew, i think a lot of us would like to see a thread on this. would be very handy to know how to do this conversion.
                    WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?

                    Comment

                    • SurrealMustard
                      Badcaps Veteran
                      • Jan 2015
                      • 486
                      • The United States of America

                      #11
                      Cool idea, but is the transfomer bypass feasible on this one?

                      That sounds very interesting and while I would love to see what that process looks like, this particular Sharp isn't mine and I'm on a bit of a time cruch to get it sorted, so I was hoping that somebody had a suggestion for the "easy fix," bypassing the transformer for the downed lamp. Any ideas for how to do it on this particular inverter?

                      Comment

                      • dick_barton
                        Badcaps Legend
                        • Aug 2015
                        • 6642
                        • Wales

                        #12
                        Re: Bad backlights suspected on Sharp LC-C5255U LCD

                        If it's a tube fault then they appear to be available from
                        http://hdtvparts.net/products/3169-l...2d85u-lc-.aspx
                        Willing to help but I'm no expert.

                        Comment

                        • culcuhain
                          Senior Member
                          • May 2016
                          • 186
                          • U$@

                          #13
                          Re: Bad backlights suspected on Sharp LC-C5255U LCD

                          Also one of those inverters might have failed. You might be able to just find the wrong inverter, replace it and be good. I did this on a 32" I had. $7 for the part and tv was back in business.

                          Comment

                          • Andrew F. Ali
                            Badcaps Legend
                            • Jan 2014
                            • 2450
                            • Trinidad & Tobago

                            #14
                            Re: Bad backlights suspected on Sharp LC-C5255U LCD

                            Originally posted by attainteddragon
                            andrew, i think a lot of us would like to see a thread on this. would be very handy to know how to do this conversion.
                            I'll format a document and post it for review, soon.

                            Comment

                            • attainteddragon
                              Badcaps Veteran
                              • Apr 2013
                              • 764
                              • australia

                              #15
                              Re: Bad backlights suspected on Sharp LC-C5255U LCD

                              Originally posted by Andrew F. Ali
                              I'll format a document and post it for review, soon.
                              awesome, looking forward to it.
                              WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?

                              Comment

                              • attainteddragon
                                Badcaps Veteran
                                • Apr 2013
                                • 764
                                • australia

                                #16
                                Re: Bad backlights suspected on Sharp LC-C5255U LCD

                                pic of the inverter board please.

                                have you checked the output windings on the transformers yet?
                                Last edited by attainteddragon; 05-30-2017, 06:44 PM.
                                WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?

                                Comment

                                • SurrealMustard
                                  Badcaps Veteran
                                  • Jan 2015
                                  • 486
                                  • The United States of America

                                  #17
                                  I'd like to; how?

                                  Originally posted by attainteddragon
                                  pic of the inverter board please.

                                  have you checked the output windings on the transformers yet?
                                  I haven't yet. Any advice on how to do so?
                                  Attached Files

                                  Comment

                                  • attainteddragon
                                    Badcaps Veteran
                                    • Apr 2013
                                    • 764
                                    • australia

                                    #18
                                    Re: Bad backlights suspected on Sharp LC-C5255U LCD

                                    measure the resistance on the output pins of each transformer.
                                    i havn't had to look at this type, but looks like one transformer per ccfl.

                                    power off of course.

                                    the one that relates to your non illuminated ccfl may of failed.
                                    if it has, it will have a noticeable difference of resistance compared to the others on the inverter board.
                                    if so, you can replace it and have the tv fully functioning without any bypassing needed.
                                    Attached Files
                                    WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?

                                    Comment

                                    • SurrealMustard
                                      Badcaps Veteran
                                      • Jan 2015
                                      • 486
                                      • The United States of America

                                      #19
                                      Infinite resistance!

                                      Originally posted by attainteddragon
                                      measure the resistance on the output pins of each transformer.
                                      i havn't had to look at this type, but looks like one transformer per ccfl.

                                      power off of course.

                                      the one that relates to your non illuminated ccfl may of failed.
                                      if it has, it will have a noticeable difference of resistance compared to the others on the inverter board.
                                      if so, you can replace it and have the tv fully functioning without any bypassing needed.
                                      I'm getting infinite resistance on all of the transformers when testing those output pins with the multimeter. It's not an auto-ranging meter, but I've gone to each transformer and ratcheted through all of the different resistance testing options to no avail. Am I doing something wrong?

                                      Comment

                                      • dick_barton
                                        Badcaps Legend
                                        • Aug 2015
                                        • 6642
                                        • Wales

                                        #20
                                        Re: Bad backlights suspected on Sharp LC-C5255U LCD

                                        Pinout of transformer
                                        Attached Files
                                        Willing to help but I'm no expert.

                                        Comment

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