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Samsung UN55D6420UF Power Cycling

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    Samsung UN55D6420UF Power Cycling

    Hello all. Found this forum while researching an issue with my TV. The thread that drew my attention was this one:

    https://www.badcaps.net/forum/showth...+power+cycling

    Decided to start an account and see if I could get mine figured out as well. My TV now has essentially the same issue, just after power up it begins to continually cycle off and on and continues a few times after unplugging. Mine didn't start this bad though. It started doing this a few weeks ago. After a few minutes of being on it would cycle once or twice and then be fine the rest of the time it was on, I even got it to not do it for a few days by unplugging it while it was on and leaving it over night. But it eventually began again and culminated last night when it began to be a continuous problem. I again unplugged it over night and was able to get to a picture for about 30seconds tonight before it began again.

    Because mine hasn't been constant I was wondering if it might be something other than a bad LED as in the other thread. I called a local repair place that I got off of the samsung site, gave them my model and told them the issue and was quoted $270 to fix it. While I'm no electrical engineer, I know my way pretty well around the inside of electronics so I decided to take a look before dropping three hundred for someone to fix it.

    Below are pictures of what I am working with. Where should I begin? And thanks in advance.




















    #2
    Re: Samsung UN55D6420UF Power Cycling

    Ok.....so, with the back off of the TV and it leaning screen down against the back of my couch, I plug it in and now it's working. It hasn't cycled off once in 5 minutes. I bulged the back panel back in and have turned it on and off with the factory remote, the back panel and my universal remote. It's just sitting there mocking me.

    Comment


      #3
      Re: Samsung UN55D6420UF Power Cycling

      OK, check and see if all the connectors are seated properly, also check and tighten all the circuit board mounting screws to make sure they are tight since the board is grounded to the chassis through the mounting screws. You also can have bad solder joints on the board, so use a wooden stick, or plastic stick to press on the board to see if you can make it go out.
      Last edited by budm; 07-11-2014, 09:07 PM.
      Never stop learning
      Basic LCD TV and Monitor troubleshooting guides.
      http://www.badcaps.net/forum/showthr...956#post305956

      Voltage Regulator (LDO) testing:
      http://www.badcaps.net/forum/showthr...999#post300999

      Inverter testing using old CFL:
      http://www.badcaps.net/forum/showthr...er+testing+cfl

      Tear down pictures : Hit the ">" Show Albums and stories" on the left side
      http://s807.photobucket.com/user/budm/library/

      TV Factory reset codes listing:
      http://www.badcaps.net/forum/showthread.php?t=24809

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        #4
        Re: Samsung UN55D6420UF Power Cycling

        I put it back together for the night. I checked the function after each panel was reinstalled and it was fine. Once I hung it back on the wall it started to act up but only once or twice. Then I was shifting it on the wall mount and as it slid roughly across it it cycled off and on one time. So I did it again and it did it again. May be a loose board or bad solder. I'll pull it back apart tomorrow and check things as you recommended.

        Comment


          #5
          Re: Samsung UN55D6420UF Power Cycling

          Ok, so the acting up has gotten bad again. Pulled it back off the wall this morning and took the back panel off again. All of the boards seem to be secure, screws were all tight. Once I got it to stay on I started to lightly press on components on the PS boars with a small piece of wood. Every time I put a little pressure on the lower left of this component it would cycle the power. The top and lower right didn't do anything, only the lower left of it. I did it several times to make sure it wasn't a fluke. None of the solder joints appear to be loose or broken.



          Comment


            #6
            Re: Samsung UN55D6420UF Power Cycling

            If I were you I would resolder all connections on that transformer and surrounding areas including the MOSFET transistors next to it.
            Did I leave the soldering iron on?

            Comment


              #7
              Re: Samsung UN55D6420UF Power Cycling

              There of course could be a bad connection in that transformer as well.
              Did I leave the soldering iron on?

              Comment


                #8
                Re: Samsung UN55D6420UF Power Cycling

                I haven't had a chance to try resoldering yet. I was messing with it a little more this evening. Once it would start cycling the power, if I grabbed that transformer by the plastic lip and pulled on it a little, the cycling would stop and the TV would be fine. As soon as I let go it would begin cycling again. I did this several times with the same results. Also, everytime the power cycles there is a pop/click coming from that transformer.

                Comment


                  #9
                  Re: Samsung UN55D6420UF Power Cycling

                  I would check mosfet solder joints. I had one that had two cracked joints. Resoldered it and it was fine

                  Comment


                    #10
                    Re: Samsung UN55D6420UF Power Cycling

                    My money is on this solder joint(see pic) (Not that I have money...lol)
                    Attached Files
                    Proud owner of dozens of broken TV's and many,many,many boards.


                    Our website and passion:http://hollenhundshepherds.com/

                    Comment


                      #11
                      Re: Samsung UN55D6420UF Power Cycling

                      Yeah, I have the back of the board another good look last night, focussing my attention around that transformer and that is the only solder connection that looked at all out of place

                      Comment


                        #12
                        Re: Samsung UN55D6420UF Power Cycling

                        Originally posted by martino View Post
                        My money is on this solder joint(see pic) (Not that I have money...lol)
                        Just got home from work. Grabbed the board and gave the line leading to that joint a little wiggle and the solder joint wiggled right along with it. Hopefully that's all it is

                        Comment


                          #13
                          Re: Samsung UN55D6420UF Power Cycling

                          That will be all it is yes. What did I win? Lol
                          I would however resolver the other joints at that transformer as well and the mosfets to the right of it, to prevent havi g to do those in 6 months.
                          Proud owner of dozens of broken TV's and many,many,many boards.


                          Our website and passion:http://hollenhundshepherds.com/

                          Comment


                            #14
                            Re: Samsung UN55D6420UF Power Cycling

                            Well, I just did the one for now. Everything seems solid. I gotta say, a little investigation and 5 minutes with a soldering iron definitely beats paying someone $300 to try and fix it.

                            Thank you all for your help!

                            Comment


                              #15
                              Re: Samsung UN55D6420UF Power Cycling

                              ssracer I am having the same problem as you so thank you for helping. I am definitely going to take back cover off and look around. We have the same tv with the same version #, build date, and all. Can you tell me what "type" panel you have in the service menu. I messed with mine when trying to find out what was going on before i read your post. I dont recall what it was on but willing to bet they are the same. Thanks for your help

                              Comment


                                #16
                                Re: Samsung UN55D6420UF Power Cycling

                                Not sure what you're asking there. Tell me where to find that and I'll look it up

                                Comment


                                  #17
                                  Re: Samsung UN55D6420UF Power Cycling

                                  Thank god for you guys. I have been having the same issue for what seems like a year and I finally (emphasis on finally) decided to fix this damn thing. Samsung UN55D6420UF powering on and off. Did quite a bit of research and saw capacitors was a common problem but once I took it apart I found the transformer looked like crap. Connections almost seem fried or melted. I am considering buying a new power board but they are hard to find. Not a professional solderer but any help you guys can give me is greatly appreciated!
                                  Images are not the best but hopefully you get the picture
                                  Attached Files

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