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Samsung TV fixed itself? (UN40D5500 series)

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    Samsung TV fixed itself? (UN40D5500 series)

    Hi,
    My 40" Samsung TV (bought in 2011 or 2012) for the last couple of weeks would power on fine in the morning, but then would reboot a few minutes later. Within 10 to 15 minutes, it may reboot 2-3 times. After these reboots, the TV was fine for the rest of the day. Recently, it started to get worse with it taking longer to come out of the reboot, and rebooting 6 or 7 times every morning or whenever you powered it off for an extended time and powered it back on.

    I decided to take it apart to look for swollen capacitors, too much dust, etc. I didn't find any build up of dust nor any swollen capacitors. I tried to test the large 100uf capacitor shown in the photo (1) but inadvertently shorted the 2 legs causing a large spark. TV however still powered on ok after that so no damage. With the power on (I forgot), I ended up accidentally shorting the + of the capacitor to the MOSFET heatsink (2) causing another large spark, and taking a small chunk from the heatsink. This time the TV did not power on and the 6.3A slow blow fuse (3) blew. I replaced the fuse with a 4 AMP normal fuse and was able to get the TV to power up again. I did finally correctly test the large capacitor when the fuse was blown and it showed about 91 uF.

    Not finding anything wrong, I re-assembled the TV, and put it back in service, and the rebooting issue hasn't occurred since for the last 3 days!

    How is this possible? Did the short take out a defective but unnecessary component?
    Attached Files

    #2
    Re: Samsung TV fixed itself? (UN40D5500 series)

    from your story it seem dust problem with wet weather in room make short contact / Spark discharge .. tv turn off.... or you have cracked soldering point on PWB,, get in contact now after you remove the board out.

    Comment


      #3
      Re: Samsung TV fixed itself? (UN40D5500 series)

      Its not dust or humidity as there was hardly any dust when I opened it up.

      Comment


        #4
        Re: Samsung TV fixed itself? (UN40D5500 series)

        then cracked solder joined. being on Transformer legs or some where ells. rework soldering if the reboot come again.

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          #5
          Re: Samsung TV fixed itself? (UN40D5500 series)

          Could it have been a cracked solder joint on the fuse I replaced? Would you see that kind of behavior?

          Comment


            #6
            Re: Samsung TV fixed itself? (UN40D5500 series)

            Sounds a bit like Flash memory that plays up, start fine in the morning when tv is cold but then cause a problem after being in use and warm up 🤔

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              #7
              Re: Samsung TV fixed itself? (UN40D5500 series)

              Its actually the opposite. Has problems when its cold, but once it warms up it no longer reboots

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                #8
                Re: Samsung TV fixed itself? (UN40D5500 series)

                Originally posted by lmcancu View Post
                Its actually the opposite. Has problems when its cold, but once it warms up it no longer reboots
                this behavior related to caps.

                Comment


                  #9
                  Re: Samsung TV fixed itself? (UN40D5500 series)

                  I did check for leaks or bulges and did not find any. But since I opened it up, inadvertently blew the fuse while checking the caps, replaced fuse and put it back together, it has been working flawlessly ever since for the last few days. No rebooting at all

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                    #10
                    Re: Samsung TV fixed itself? (UN40D5500 series)

                    there are so many matter could happend to caps.. not only leaks or bulges ... loss the legs from inside etc can happen too.. esr value... etc

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                      #11
                      Re: Samsung TV fixed itself? (UN40D5500 series)

                      Yes I understand the esr, etc. But why does TV now work ok if one or more caps are bad?

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                        #12
                        Re: Samsung TV fixed itself? (UN40D5500 series)

                        sometime taking out power connectors and putting back cleans rust and dust built on joints and problem is solved.

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