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Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

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    #1

    Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

    Hi Team - just joined to see if anyone can offer some expertise in diagnosing an issue with a TV.

    I've done a few hours googling and youtubing but just seeing if anyone has any insight here. I got a 55" Samsung UE55MU6470U which seems to boot loop and then after 10 mins will boot, work for a few minutes, then turn off and repeat.

    Whilst it's on into the normal Samsung menu/boot screen it looks perfect - so I can't see there being any screen issues. I've seen lots of videos with taping across clock lines to diagnose which particular one may be an issue but i don't think it's worth it given sometimes it will boot.

    The cycle is:
    >Black screen with "Samsung Smart TV" white text
    >blank > to black screen with the same test (but top left of that seems to fade out slightly)
    >Repeat until 1 time in 10 minutes it will boot normall and be fine.


    I took the screen apart and disconnected the left and right ribbon cables separately and with either/none the backlight comes on and stays on. With Left OR Right plugged in ONLY the backlight will come on and stay on.
    When BOTH are plugged in on the first time after (uplugging either side ribbon cable) it will boot straight away - then will go back into boot loop cycle.

    Given the main (power) board is £25, and the "TCON" board is £40 - i feel like i should just buy one to see if that works.

    Ideally looking to see if anyone's knowledge would lead it to be suspect of either of the boards. My first thought was power issue as it works sometimes - but then with the ribbon cable removed issue i think TCON board is more likely.


    Any guidance or ideas would be great.

    I'll grab some pictures if there's anything specific you think i should be looking at.

    Thanks - Z
    Tags: None
    #2
    Re: Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

    I have the same issue with my "55 Samsung - did you find a solution?

    Comment

      #3
      Re: Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

      For a quick test try #2, that's on the powerboard.

      Comment

        #4
        Re: Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

        My thinking is if it were an issue with the panel you would not be able to boot at all and the TV would give no display with flashing error codes at the status light.
        Chances are its also not a backlight issue either.

        Bcos you are also having video distortions my guess is a video related ICs ball grid array is starting to go. This is on the mainboard. A refball is necessary to rectify it. Some have temporary success by heatig the chip to get the solder beads to reorient themselves. This is called a reflow and i have never known this fix to last very long though.

        I dont know of a way to test this theory in a nondestructive manner. Your best bet would be to order a replacement mainboard and see if it curse your issue. You didnt mention the price of a mainboard. Not sure if having the chip reballed is an economical option but it usually isnt.

        Good luck and keep us posted.

        Comment

          #5
          Re: Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

          Originally posted by torchzack View Post
          Hi Team - just joined to see if anyone can offer some expertise in diagnosing an issue with a TV.

          I've done a few hours googling and youtubing but just seeing if anyone has any insight here. I got a 55" Samsung UE55MU6470U which seems to boot loop and then after 10 mins will boot, work for a few minutes, then turn off and repeat.

          Whilst it's on into the normal Samsung menu/boot screen it looks perfect - so I can't see there being any screen issues. I've seen lots of videos with taping across clock lines to diagnose which particular one may be an issue but i don't think it's worth it given sometimes it will boot.

          The cycle is:
          >Black screen with "Samsung Smart TV" white text
          >blank > to black screen with the same test (but top left of that seems to fade out slightly)
          >Repeat until 1 time in 10 minutes it will boot normall and be fine.


          I took the screen apart and disconnected the left and right ribbon cables separately and with either/none the backlight comes on and stays on. With Left OR Right plugged in ONLY the backlight will come on and stay on.
          When BOTH are plugged in on the first time after (uplugging either side ribbon cable) it will boot straight away - then will go back into boot loop cycle.

          Given the main (power) board is £25, and the "TCON" board is £40 - i feel like i should just buy one to see if that works.

          Ideally looking to see if anyone's knowledge would lead it to be suspect of either of the boards. My first thought was power issue as it works sometimes - but then with the ribbon cable removed issue i think TCON board is more likely.


          Any guidance or ideas would be great.

          I'll grab some pictures if there's anything specific you think i should be looking at.

          Thanks - Z
          Yes, ALWAYS pictures, need good straight on focused pictures of each board and one of the whole back as to see how everything is connected.

          Comment

            #6
            Re: Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

            Simple test, with tv unplugged from power, unhook cable from powerboard to mainboard, leave it off, plug tv into power, do backlights come on and stay on.

            Comment

              #7
              Re: Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

              Mu series Tvs seem to have a lot of eeprom issues. Could be bad eeprom chip or it’s starting to go corrupt. You can try freezing the chips then powering on to see if any change. These are always Winbond chips in my experience.

              Lotas usually assist everyone here with fixing there eeprom software if you have a programmer/ reader.

              Comment

                #8
                Re: Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

                My guess is it's still the panel. Pictures would help though, are you disconnecting each side of the ribbon cables coming from tcon to panel driver? If you are, try disconnecting a panel driver cable to panel driver cable instead. No pictures to see if there is two cables but just an idea.

                I would also just try a piece of tape on each side of the cable anyways since you can quickly move the tape a few times and cover like 8 pins turn it on and off, if one of those gets it to stay on for a bit then that's probably your answer. YouTube fixing Samsung with tape if you don't already know.

                But it is odd that sometimes it "turns on"

                Bootloop I believe is not usually power board or TCON, I would definitely not buy those parts until you do some tape method.

                Comment

                  #9
                  Re: Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

                  #6 I have unplugged the cable as per your instructions and the backlight came on and stayed on.

                  Attached are some photos.
                  Attached Files

                  Comment

                    #10
                    Re: Samsung 55" TV - Boot loop but sometimes works fine - UE55MU6470U

                    Ok, that in most cases means the backlights and powerboard are alright, so you can concentrate on the rest.

                    Comment

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