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Sharp LC-70LE757U flickering display

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    #1

    Sharp LC-70LE757U flickering display

    Recently while watching TV, the display suddenly went bad.
    This was not recorded by me, but shows the exact problem my TV is having:
    https://www.youtube.com/watch?v=bxQE83bc3yc

    When powering up the set, the picture first looks perfect for 1-2 minutes. Then it will start with the flickering and horizontal black bars going up and down. It doesn't seem to snap back to normal without powering the TV down and powering it back up. The flickering is apparent across all inputs and menus.

    I'm trying to identify if it is a bad panel, or perhaps a t-con board (or other board) issue that can be fixed.

    I tried pulling the right-most t-con ribbon cable from the board and the flickering immediately stops and one half (right) of the picture looks perfect.
    http://imgur.com/eSKg2gl

    I tried pulling other combinations of t-con cables with different results. Most giving me a 2-5 blink pattern.

    Unfortunately, these TV's failing seems to be a trend recently. I saw some other threads where people had luck disabling one side's drivers. I don't know if this fix would apply to this set?

    Should I order a replacement t-con board on eBay and cross my fingers?

    Thanks!
    Tags: None
    #2
    Re: Sharp LC-70LE757U flickering display

    I don't know if this means anything. But here are a few additional observations.
    After I started pulling t-con cables and testing, now when they are all plugged in normally it immediately has the flickering display issue (not after 1-2 minutes).

    Also, I tried powering on/off the TV several times and now the display is not flickering and is not dark like before, but still has the large black horizontal bars going up and down the screen.

    Comment

      #3
      Re: Sharp LC-70LE757U flickering display

      Further observations:

      When the far right t-con cable is disconnected I get a clear picture on the right (no flickering).

      When the far left t-con cable is disconnected I get a picture on the left, but with the flickering.

      I also noticed a buzzing sound coming from the t-con board when the far right cable is attached. If I disconnect that cable, no buzzing and no screen flickering.

      Could this indicate that one side is faulty?

      EDIT:

      I tried disconnecting the ribbon cable on the bottom right on the frame of the tv (not sure what these are called), which results in no flickering but a dark (left) half of the screen.

      If I disconnect the left side cable, I get the flickering.
      Last edited by grizgza; 11-02-2015, 03:13 PM.

      Comment

        #4
        Re: Sharp LC-70LE757U flickering display

        Can you take a picture of what the screen looks like with anything but a black background like maybe a white screen or a blue screen see if the black bars are darker on one side. It sounds like a short in right-hand tab drivers
        Did I leave the soldering iron on?

        Comment

          #5
          Re: Sharp LC-70LE757U flickering display

          Here is a photo on white background.
          http://imgur.com/7PIboMG

          I can't tell if the bars are any darker on either side. But I do see 2 anomalies on the left side of the screen. In the bottom left there is a little diagonal line, that seems permanent. There also seems to be a dark shadow on the middle left side on the bottom half of the screen. You can see both of those things in the photo. The right side looks more uniform.

          Comment

            #6
            Re: Sharp LC-70LE757U flickering display

            I just noticed that my comments on which side were clear when unplugging t-con cables is reversed. I need to make sure I get the side right lol.

            When I unplug the right most (when looking at back of tv) t-con cable, the right side of the TV is perfect with no flickering.

            When I unplug the left most t-con cable, there is still flickering across the whole panel.
            Last edited by grizgza; 11-02-2015, 03:18 PM.

            Comment

              #7
              Re: Sharp LC-70LE757U flickering display

              With right side frame ribbon cable in bottom right disconnected:
              http://imgur.com/unIHYDM

              With right side t-con cable removed:
              http://imgur.com/28ZzD5d

              Comment

                #8
                Re: Sharp LC-70LE757U flickering display

                I would say that looking at the front of the TV the left side driver tabs there is some sort of problem. Now if you can dig into this a little deeper can you pull the black side metal frame off the panel and very carefully disconnect the white cable going to that side? It is about three quarters in length and is connecting to the bottom of the left side side drivers? This is looking at the side of the panel on the left side of the TV facing the front. This cable is located on the left side near the bottom. It will look like this .

                Once you do this power of the TV and see if the flickering persist. Most likely what you're going to see how is the left side is going to be darker then the right. But what I'm looking for is any horizontal lines going across the screen
                Attached Files
                Last edited by freakaftr8; 11-02-2015, 03:45 PM.
                Did I leave the soldering iron on?

                Comment

                  #9
                  Re: Sharp LC-70LE757U flickering display

                  I'm now feeling fairly confident that the issue is isolated to the left half of the screen (cables on right side when looking at the back of the set). I'm thinking that removing the tab drivers on that side may fix the issue, but hesitant to go ahead and do this if it could be just a bad t-con board.

                  Is it likely that the buzzing sound on the t-con board and the screen flickering when one side is plugged in are caused by a short on the corresponding tab driver. Based on my evidence is there any chance that it is the t-con board itself that is the issue?

                  Comment

                    #10
                    Re: Sharp LC-70LE757U flickering display

                    That's what we're trying to figure out before we decide to butcher the panel. We need to rule out the t-con board. The flickering you're getting on the screen almost looks like a driver is loading down the tcon board especially the core voltage to the main processor to the point where it wants to shut down with the 2- 5 error code but its not
                    Last edited by freakaftr8; 11-02-2015, 03:48 PM.
                    Did I leave the soldering iron on?

                    Comment

                      #11
                      Re: Sharp LC-70LE757U flickering display

                      OK, I really appreciate your help.

                      I had previously disconnected the left side drivers ribbon cable at the bottom. The flickering and horizontal lines went away completely and the left side of the screen was darker.

                      http://imgur.com/unIHYDM
                      Last edited by grizgza; 11-02-2015, 04:01 PM.

                      Comment

                        #12
                        Re: Sharp LC-70LE757U flickering display

                        Ok and when it is in that state with the driver disconnected like you showed in that picture can you display something on the screen other than a white screen and actually see an image and within the image are there any horizontal lines spanning horizontally across the screen?
                        Did I leave the soldering iron on?

                        Comment

                          #13
                          Re: Sharp LC-70LE757U flickering display

                          No horizontal (or other) lines at all. Picture looks fine, just dark on left side. Also, no buzzing from the t-con board like there is when the driver is plugged in.

                          Comment

                            #14
                            Re: Sharp LC-70LE757U flickering display

                            Man that's a tough call. Possibly if cheap enough try a tcon board but I still think it's a panel problem. It's your call.
                            Did I leave the soldering iron on?

                            Comment

                              #15
                              Re: Sharp LC-70LE757U flickering display

                              I think you are seeing a driver issue. On the sharp that I looked at, the tcon did make noise when the thing was running with a "bad side". When you disconnect one side or the other, you may not actually take out the driver from the load on the overall circuit but you are reducing the load on the tcon overall because it is only "pushing" to half the screen. But as freakaftr8 indicates, there is no going back once you go that way so for sure take your time on this.... plus its only TV... you can't be missing much.... :-)

                              I think you would be wise to get a hold of some test patterns... they are on various discs both as part of "extras" and as actual test discs (wow for instance). I think this will provide you with a better "image" of what you are looking at. Further a white screen is not a good screen to look at for this problem as I found the lines aren't "dead lines", they are some form of "delay" line across the screen (ie. shifted).
                              Last edited by budwich; 11-02-2015, 04:45 PM.

                              Comment

                                #16
                                Re: Sharp LC-70LE757U flickering display

                                So I went ahead and removed the left side driver tabs from the lcd panel. And BOOOOOM it worked! Perfect picture across the screen.

                                I realize this is more of a salvage than a full repair, but I'm happy. The drivers on the other side will likely eventually go, maybe sooner than the last ones because they are doing double duty, but the set was given to me and any time I get out of it with our family I'll be happy!

                                Thanks for your help guys. Without your help and the other thread I would have never know to try this.

                                Comment

                                  #17
                                  Re: Sharp LC-70LE757U flickering display

                                  Nice fix!! Wow 3 repairs in 1 day! Let's see the pic
                                  Last edited by freakaftr8; 11-02-2015, 07:32 PM.
                                  Did I leave the soldering iron on?

                                  Comment

                                    #18
                                    Re: Sharp LC-70LE757U flickering display

                                    Nice! Here are pics of the left-side drivers removed and the TV working like new.

                                    Watching Monday Night Football and it looks glorious!
                                    Attached Files
                                    Last edited by grizgza; 11-02-2015, 08:08 PM.

                                    Comment

                                      #19
                                      Re: Sharp LC-70LE757U flickering display

                                      That doesn't look like MNF. Oh wait, the guy in the middle is Stafford so must be the Lions :/

                                      Comment

                                        #20
                                        Re: Sharp LC-70LE757U flickering display

                                        Originally posted by grizgza View Post
                                        Nice! Here are pics of the left-side drivers removed and the TV working like new.

                                        Watching Monday Night Football and it looks glorious!
                                        but if you remove them? why still picture it suppose to control the left side. add pics were you removed them. i have the same problem tv is working good it doesn't turn off. after i read your comments i though i was a bad t_con i have try on other tvs with horizontals lines and it was of bad t-con and i went by that. i disconnected one side on the t-con LC-70LE757U an it works good and i reconnected and flickering started. so tell me more about whats the function of driver guide me a bit to fix this tv thanks......

                                        Comment

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