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Samsung LNT4669FX/XAA random horizontal line and restart issues

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    Samsung LNT4669FX/XAA random horizontal line and restart issues

    Hi! I'm new here and trying to find some help. I've been searching and I'm just not confident that I've found issues that are exactly like what I have. I was given a Samsung LNT4669FX/XAA with known issues to tinker with to see if I can get it working. Apparently they had some service done to it at some point, but I'm not sure what that work was. I'm familiar with the bad caps issue and have done that repair on another TV before. I checked this one and all of the Caps look fine. So here are my symptoms:

    1) When first plugged in, the red light flashes then the TV makes the startup chime sound. The screen will come on but the image is green and snowy then it will click off then back on. It does this several times, eventually the startup sound stops playing and it just makes the click sound. After a little while, it will start up and have a great picture. It seems like a cap issue, but since they aren't damaged, I'm skeptical. Also, once it has warmed up, I can turn it off and back on after a few mins and it powers right on.

    2) Once powered up, if I add an input on any of the HDMI ports (haven't tried RCA ports) I will get a few random horizontal lines that will flash of for a split second then go away. I got a video of this. https://youtu.be/Z8dK6gRylg4. I tried 3 HDMI cables and tried my Roku and TiVo and switched the Roku between 720p and 1080p output. Nothing affected the lines. The video shows the Roku main menu and there is some ghosting or something where the menu duplicates and slides off the screen (don't know how to describe this). If I navigate off of the main Roku menu or play video from any Roku app (Netflix, Hulu, etc) or switch over to Tivo, the screen flicker and ghosting goes away and I just have the random horizontal lines that flicker on and off periodically, but there is no other flicker to the picture.

    https://youtu.be/Z8dK6gRylg4

    As for troubleshooting, at this point I visually checked the caps and they seem fine. I also fully disconnected the T-CON board and the lines don't appear. Just a black screen with a glow around the edges.

    The previous owner said it was the main board that was bad, but I'm not sure how he arrived at that conclusion. It feels like I'm dealing with 2 separate issues, but I'm not experienced enough to know for sure. I'd rather not just start swapping out parts willy nilly and I'm guessing there are some other ways to diagnose things to get a better target. Any help would be greatly appreciated.

    Thanks!

    #2
    Re: Samsung LNT4669FX/XAA random horizontal line and restart issues

    These guys have known bonding tab issues. I have a 40" version of this series that would do what you said.

    I believe that you have two issues. One is the bonding pad issue. You can sometimes put some resilient material to press the tabs down (I used a piece of plastic foam). You can easily tell which tab is giving you the problem by pressing on them individually.

    Second problem is the power supply (caps). One or more is probably bad - you just haven't found the bad ones yet. Look also on the main board for a bad cap. Monitor the voltages coming off the supply to identify problem area.

    Comment


      #3
      Re: Samsung LNT4669FX/XAA random horizontal line and restart issues

      Can we see good clear pictures of the whole back side of the TV so we can see all the board, also good clear pictures of the power supply board and the main board?
      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


        #4
        Re: Samsung LNT4669FX/XAA random horizontal line and restart issues

        These are the pics I have at the moment. I can take some more this evening and post.

















        Comment


          #5
          Re: Samsung LNT4669FX/XAA random horizontal line and restart issues

          I haven't gotten back to the TV to get pics yet. I ordered a set of caps and I also found someone on eBay selling all the boards out of this model. They should arrive this week. my plan is to swap the boards one at a time to see if anything changes. If the power board helps with the startup issue, I'm going to replace the caps. If the boards don't help the screen, I'll look at the tabs issue as well.

          Comment


            #6
            Re: Samsung LNT4669FX/XAA random horizontal line and restart issues

            I replaced the caps and seem to have the same problem. It eventually warms up and stays on but has static lines.

            https://youtu.be/ykqMAkp5JBk

            Comment


              #7
              Re: Samsung LNT4669FX/XAA random horizontal line and restart issues

              Not sure if anyone is reading this but I could use some direction.

              I got a set of used boards in and started swapping. The only change in symptoms was when I swapped the PCB SUB FRC board. When I did this, I got the white screen - black with white light only coming in from the sides and warms up to be mostly white. This makes the power cycling stop. I have switched the T-CON and the FRC boards around every way possible. If I unplug the cable coming from the main board going to the FRC, and the power cycling stops Regardless of which other boards are installed.

              So, I'm stumped. I don't know what to do next. Please help!

              Comment


                #8
                Re: Samsung LNT4669FX/XAA random horizontal line and restart issues

                I agree with the original assessment. The horizontal lines you mentioned sound like bonding tab issues. I have a HannsG monitor that shows the same symptoms. There is no fix.

                Bonding tab issues and symptoms change with the heat of the panel. When mine is cold almost half the screen is covered in horizontal lines. After an hour or so only a handful remain. Leave it on a couple days and the display is perfect. It sounds like yours is shorting out though.

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