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Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

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    Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

    Hey! I have an LN-S3241DX that I think has a bad t-con board but I wanted to check here to see if anyone had any ideas on anything else I could do to conrifm the issue

    Occasionally, colored vertical lines would appear across the screen and the screen would freeze while slowly turning black. Usually, if I just power cycled the TV this would go away.

    Slowly it's started happening more and more and starting a few days ago it would happen shortly after turning the set on. Power cycling would still work, but it would only last a short amount of time (less than 1 minute). Sometimes the screen would exhibit the symptoms and would pop back to normal before doing it again after a little while.

    I took apart the panel to see if I see anything obvious and at first, flexing the tcon board and reseating the ribbon cables seemed to help but that might have just been a coincidence. From there the symptoms got a bit worse and now it just powers on with no picture (the backlight does come on). I did run it for a bit with the panel off the main board so I could check values and that had a heatsink touching the video processing (STP03) chip which did get a bit hot to the touch.

    Here is an example of a picture I managed to get 1 time it happened (this was September of last year so it's been mostly fine for the last 4 months)


    The output voltages of the power board match the values written on the board so I don't think it's that (although there are a few caps that look a little suspect)

    Checking the connector off of the main board to the t-con the powered pins are reading 5.4v or 1.2v, The tv turns on via the remote and panel buttons and functions work (changing input, volume, setting the sleep timer - you can't see them, but I've had it long enough I can set this without needing to see the screen)

    Power levels on the t-con board seems suspiciously low. The test points near the main board connector (RX1. RX2. RX3) read 1.2v, the voltage regulator (U14) reads 2.5mV, the fuse (F1) reads between 20 and 100mv, and the value for all of the GAMMA test points fluctuate pretty wildly.

    Does that seem like a t-con issue or something else? Anything else to check?

    Thanks!
    Last edited by hotsho111; 01-13-2021, 11:52 PM.

    #2
    Re: Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

    Hi

    With this sort of symptom , i would be looking at either T-CON , or display itself .

    Very unlikely to be caused by main board .

    Regards Zen

    Comment


      #3
      Re: Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

      I'd throw a replacement tcon at it, see what happens, they should be pretty reasonable for a 32 inch tv.

      Comment


        #4
        Re: Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

        Cool! I thought that might be the case so I'll try that and let you know how it goes. Thanks!

        Comment


          #5
          Re: Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

          Quick update, I purchased a t-con board but the order got cancelled because it was out of stock.

          I'd disconnected the tcon board before and noticed the LVDS cable wasn't fully seated. I reconnected that and now I'm back to having a picture that occasionally glitches out.

          I did take readings of a whole bunch of components on the tcon board when the picture looked normal and they all read what more like I'd expect. The picture did get distorted a couple times while I was measuring values and when that happened they would wildly change (I didn't notice if the levels went up or down but I think they went down)

          Would that still indicate tcon board issues or possibly a power board issue?

          Comment


            #6
            Re: Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

            Quick follow up question. It seems like the issue is related to one of the voltage regulators (MMC6100B) so I'm going to replace that, but they are all reading slightly off so I was thinking of picking up two others.

            The others are labeled L1117DG and L1117LG-33. Does anyone know suitable replacements for these (the latter has been a little easier to search for)? L1117DG is reading 3.5V on the output so I'm not sure if that should be a 3.3V or 5V one
            Last edited by hotsho111; 01-17-2021, 11:44 PM.

            Comment


              #7
              Re: Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

              The L1117LG-33 is a 3.3V fixed regulator.
              L1117DG is an adjustable regulator

              https://www.datasheetq.com/datasheet...ko-Sem/L1117DG

              Page 5 shows the arrangement for the adjustable regulator chosing R1 and R2
              Last edited by dick_barton; 01-18-2021, 05:16 AM.
              Willing to help but I'm no expert.

              Comment


                #8
                Re: Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

                Thanks Dick, I ended up just ordering the 1 voltage regulator and a bunch of caps for the power supply which should be in this weekend.

                Comment


                  #9
                  Re: Debugging Vertical Lines/Freezing on Samsung LN-S3241DX

                  Hey, just following up, swapped out U14 LD1117S25TR‎ and the tv is working now.

                  I'm still gonna swap out the caps but just wanted to follow up on the fix.

                  Thanks everyone!

                  Comment

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