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Sony KDL-52XBR4 - DTV color flicker

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    Sony KDL-52XBR4 - DTV color flicker

    Was brought a KDL-52XBR4 yesterday and have been tracking down some problems. It's been touched by someone else as well, not really reassembled very well.

    I'm down to a question about either the main board or the tuner board.
    I am having a problem with DTV video which can be seen in the video below.
    Also included some fix history below, but for the TLDR people:

    All inputs work, getting full screen single color flashes when trying to use the HD/DTV side of the tuner.

    SD/Analog produces static as expected, no problem. All other inputs work ok.

    ATSC Transport stream is being parsed, and decoded, sound will playback, video will not. Transport/prog stream information like channel id, CC, resolution and such are all getting parsed and display in the infobar.

    Flicker happens before and during decoder buffer fill, ie while changing channels, so I don't think this to be the decoder itself?

    The ribbon cable may have been toyed with, I will attemp to reseat that, once I remove the shields.

    Otherwise should I just replace the tuner board? It's cheap, if the tab bonding fix works, I'll go that route no problem, not worth fixing if not
    Does anyone think that this is a problem related to the main board?
    I personally think it's the tuner, but figured any extra input is always valuable.

    Skip to 2:50 for the flickering
    https://www.youtube.com/watch?v=yRgpLJh9bNU


    Thanks

    ---------------

    Previous problems with set, haven't checked service history menu yet.

    Black screen - Green Power led, sits on for 10-20s then shuts off, standby blinked 5 times.
    Read here appears to be some kind of T-con failure.
    Checked all fuses on UB1, no problems, moved to the Samsung board above UB1, found a dead F1 fuse. LF5A, littlefuse 5A.
    After talking with the person in the tv before,this was cause by not letting the tv discharge before unplugging cables. Just went black on him, fighting the tab bond problem.

    Was midnight and only had 2, 6.3 and 8A fuses, so I put in a 2A thinking it would blow, but the TV powered up and I started to get a ton of vertical lines, with menu and everything fine in the background. The lines we R B G W, close together space about an inch apart, repeating.
    I noticed when flexing the tv the lines would change, so I assumed it to be a tab bonding problem.
    The top seals are all good there, so luckily no one has messed with those connection yet. Giving the top area some taps , I found the spot where it changed and gave it a good knock instead of a tap, perfect picture. Luck.
    I haven't moved it, but I plan to pull the panel edge back and fix it with 2 sided tape and fish tank airhose. I've done it with tab bonding problems in the past and it works well, even through moves.
    Lay the two sided tape on top of the ribbons, all along the top board(s), then stick the airhose to the tape, then put the cover back on to compress the airhose and press the ribbon against the board(s).
    Cheap, and works unless the panel is bad or the ribbons burnt , ribbon chip crack, fails.

    Will grab a fuse today so I can get the heatsinks back on properly and give it some run time. But any ideas about the tuner would be appreciated.

    #2
    Re: Sony KDL-52XBR4 - DTV color flicker

    Well my guess is pretty much wrong now.
    but I've narrowed down the symptoms a little more.

    I removed the tuner board, ribbon and connector, still had the flickering problem.
    Analog was black,which was expected.
    Re-installed the tuner board.

    Powered on the tv, quick flicker, attached the antenna, the flicker slows, goes mostly green/black/pink, dimmer. I notice this a little in my first video when I have no signal, the flickering gets more intense. So I tuned in a channel, flickering slowed, turned on PIP and there is picture!
    Exit PIP, flashing and or black.

    So the tuner works, and now I'm led to believe that there is a problem on the main or input board. The tuner connects to both of them. I'll have to start looking into the service manual a little deeper and maybe find out how things are 'routed'. Might shed some light as to which board.
    Any ideas appreciated

    PIP video showing working tuner/video in PIP but no video FS.
    https://www.youtube.com/watch?v=Fkwn7rrgRUo

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      #3
      Re: Sony KDL-52XBR4 - DTV color flicker

      Tuner problem resolved!

      Got a new main board today and it solved the full screen tuner flicker problem. Now I have to solve the intermittent vertical line issue.
      I'd guess it's the tcon board or maybe the UB1 board.


      Board replaced, Vertical Lines on TV, but the tuner works.
      https://www.youtube.com/watch?v=4ERuVWYNmOk

      Tv comes back
      https://www.youtube.com/watch?v=ppHjMKe7dWM

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