Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

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  • timleferink
    New Member
    • Jul 2017
    • 8
    • Netherlands

    #1

    Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

    Hello to everyone here!

    I've learnt a lot while searching this forum for a few devices before, but unfortunately I've now got a problem I really can't find any info on.

    Recently, I got a Samsung UE40D6530 that has an interesting issue:

    After being turned off for an hour or so, it turns on, displays a picture properly for between 5-20 minutes. Then the picture becomes distorted, starts flickering, turns to black and then the infamous relay clicking starts. Power cycling the device leads to more black screen and relay clicking.

    To clarify: see here: Youtube video

    I've checked the voltages from the power supply and they all seem good and stable (checked with a proper oscilloscope). This seems to make sense considering how long the TV continuous functioning. The caps don't look buldged or anything.

    As the picture becomes distorted before the real problem starts, I suspect either the mainboard or the TCon board. Disconnecting the TCon board does not stop the relay switching on and off.

    Can I now assume that the problem lies in the mainboard?

    If so, are there some pointers to what voltages/caps etc to check?


    For reference I included a picture of the Mainboard (BN94-05035G) and the PSU (BN44-00427A).
    (note the black spot on the PSU was from when I connected my ground clip to this pin, apparently it's not floating as I expected :P . My 6A breaker blew, all fuses stayed intact and the functionality of the device was not affected).

    I'm afraid that because it works for multiple minutes, and then not for an hour, it might be heat related, and off course the main processing chips get the most hot.

    Also, I'm not afraid of soldering SMD components, but reballing a CPU/DSP is a stretch. If all else fails I'm willing to give it a try though .

    Thanks in advance,

    Tim Leferink
    Attached Files
  • zomi
    Badcaps Veteran
    • Nov 2011
    • 505

    #2
    Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

    Disconnect mainboard
    and see if backlights come on and stay on

    Comment

    • timleferink
      New Member
      • Jul 2017
      • 8
      • Netherlands

      #3
      Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

      Originally posted by zomi
      Disconnect mainboard
      and see if backlights come on and stay on
      Forgot to mention this, sorry! The backlight turns on and stays on.

      Comment

      • sordids999
        Badcaps Legend
        • May 2013
        • 2149
        • uk

        #4
        Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

        I think I've seen this before in a previous post where the legend connections at the power supply and is suspect but I may be wrong but check each wire connection
        Also what's the black area around the bridge rectifier ?
        Last edited by sordids999; 03-06-2018, 05:45 PM.

        Comment

        • freakaftr8
          Badcaps Legend
          • Oct 2012
          • 3743
          • USA

          #5
          Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

          This is similar to the problem that the A series had with a bad C102. It's probably a dad capacitor somewhere on the main board that runs nvram. I would take a can of freeze spray in start hitting the board in various areas when it develops the problem and see if the TV comes right back on.
          Did I leave the soldering iron on?

          Comment

          • timleferink
            New Member
            • Jul 2017
            • 8
            • Netherlands

            #6
            Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

            Originally posted by sordids999
            I think I've seen this before in a previous post where the legend connections at the power supply and is suspect but I may be wrong but check each wire connection
            Also what's the black area around the bridge rectifier ?
            I'll do a double check, though the device seems very clean (no dust etc), I've also reconnected all cables.
            The black area is where I mentioned I connected my ground probe on my oscilloscope .

            Originally posted by freakaftr8
            This is similar to the problem that the A series had with a bad C102. It's probably a dad capacitor somewhere on the main board that runs nvram. I would take a can of freeze spray in start hitting the board in various areas when it develops the problem and see if the TV comes right back on.
            Thanks for the info! I've ordered some freeze spray and will try this tomorrow, I'll keep you posted.

            Comment

            • timleferink
              New Member
              • Jul 2017
              • 8
              • Netherlands

              #7
              Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

              Got the freeze spray in today. After some testing the tv indeed turns on again!

              After a while we found that the problem seems to arise in the spot attached below, or at least in close proximity. A little spray: backlight, then it turns off after a few seconds (up to 10s). Checked all the caps closeby, but no shorts.

              To make sure it wasn't a bad connection I resolderded the crystal, caps and resistor. After this the tv turned on for 30 minutes, weird!

              Then the audio stopped intermittently, then in its entirety, fuzzy image, clicking relay. I didn't have the speaker on before, so this might shed a clue for someone.

              Sprayed some more freeze spray, image. I touch the crystal, tv turns off instantly!

              Could the crystal be faulty?? Or should I look at the caps that run the crystal?


              Thanks!

              Tim
              Attached Files
              Last edited by timleferink; 03-08-2018, 06:33 PM. Reason: Crystal, or caps?

              Comment

              • freakaftr8
                Badcaps Legend
                • Oct 2012
                • 3743
                • USA

                #8
                Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

                When you freeze the crystal if it goes out of frequency it's coming back into frequency or somewhere close. I would say either a bag crystal or some resistance change within the crystal. Swap it out 1st get the specs on the top of the cap of the crystal.

                Looks to be a 24.000MHZ
                Last edited by freakaftr8; 03-08-2018, 09:49 PM.
                Did I leave the soldering iron on?

                Comment

                • timleferink
                  New Member
                  • Jul 2017
                  • 8
                  • Netherlands

                  #9
                  Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

                  Got a new 24MHz crystal in today, and indeed, everything works!

                  Thanks to everyone for helping out! The freeze spray tip was new to me, this is great when you can't easily take the board out and use alcohol, and also, in this case it probably wouldn't have worked.

                  Soldering the crystal with a regular soldering iron was a bit difficult as shown in the picture, should have used my hot air gun (would have saved the pads under the crystal... ).

                  Tim
                  Attached Files

                  Comment

                  • nomoresonys
                    Badcaps Legend
                    • Jan 2013
                    • 12081
                    • U.S.

                    #10
                    Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

                    Well done Freakaftr8, you named that tune (solved the case) in 2 posts.

                    Comment

                    • freakaftr8
                      Badcaps Legend
                      • Oct 2012
                      • 3743
                      • USA

                      #11
                      Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

                      Good to hear!
                      Did I leave the soldering iron on?

                      Comment

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

                        #12
                        Re: Samsung UE40D6530, fuzzy image after a few minutes, then relay switching

                        Originally posted by freakaftr8
                        good to hear!
                        +1000

                        Comment

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