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    Samsung UA40J5100 LED SMPS voltage

    The v outputs on the SMPS to the MAIN are supposed to be 13v according to the writing on the SMPS board. They are all reading 12.68v when tested. Is this too low?

    The symptom is that the backlights come on but there is no picture. The LED's on the TCON do not come on (sometimes TCON LED2 will flash briefly on startup). Voltage at both sides of TCON fuse is also 12.68v.

    The power LED flashes five times after power on. After the second flash, the backlights flicker. Then after the fifth power LED flash, the backlights flicker again. Then the power LED stays off, with the backlights still on.

    Sometimes when first powered on the RF picture and sound will come on but as soon as the menu button is pressed the picture will 'melt' away.

    No puffy caps or burned components on any board (that I can find).

    Please help as I live on one of the most remote inhabited islands on Earth. No airport and a supply boat only every six months. So if I am going to get a new board for the owner of this unit I need to know it is the right one :-(
    Last edited by rowage; 02-26-2020, 03:35 AM.

    #2
    Re: Samsung UA40J5100 LED SMPS voltage

    That voltage is close enough, and not your problem, post some pictures of what we are dealing with, picture of rear with all board attached, then pictures of main, t-con etc.
    with power OFF, disconnect one of the flat cables between the t-con and the panel and see if you get half screen, if not turn off, reconnect the cable and try disconnecting the other flat cable. If you do get half a screen, you could have a panel issue
    Last edited by R_J; 02-26-2020, 10:53 AM.

    Comment


      #3
      Re: Samsung UA40J5100 LED SMPS voltage

      Originally posted by r_j View Post
      that voltage is close enough, and not your problem, post some pictures of what we are dealing with, picture of rear with all board attached, then pictures of main, t-con etc.
      With power off, disconnect one of the flat cables between the t-con and the panel and see if you get half screen, if not turn off, reconnect the cable and try disconnecting the other flat cable. If you do get half a screen, you could have a panel issue
      +1
      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

      Comment


        #4
        Re: Samsung UA40J5100 LED SMPS voltage

        Thank you fro your fast response. I have attached images as instructed. I removed the ribbon cables coming out of the TCON one at a time. Neither made any difference. No picture on either side. Just backlighting only.

        I appreciate your continued assistance.
        Attached Files

        Comment


          #5
          Re: Samsung UA40J5100 LED SMPS voltage

          I see a lot of rust and corrosion on the jumper wires etc. on the power supply board. I suspect this corrosion could be elsewhere on other boards, this could explain the intermitint nature of the problem. Check and clean all the flat cables, there are voltage test points on the t-con, check if you have the voltages (VCC_3.3V etc.)
          To determine if the fault is on the main or t-con, you need a scope to check for video signals on the lvds cable (from main to t-con)

          Comment


            #6
            Re: Samsung UA40J5100 LED SMPS voltage

            Hi RJ,

            Thank you again for your kind and fast response. I did clean (with isopropyl) and re seat all three flat cables. I have tested:

            VCC 3.3V - nothing (1.1 to 1.3mV)
            VCC 1.8V - nothing (0.2mV)
            VCC 1.15V - nothing (0.1mV)

            Both sides of fuse on TCON are still 12.68V. I do not have an oscilliscope to check the LVDS cable sorry.

            Then I saw the test points for the LVDS input to the TCON so I tested those. As per picture:

            1: 12.7V
            2: 0.531V

            3: 0.718V
            4: 0.672V
            5: 0.667V
            6: 0.681V
            7: 0.486V
            8: 0.578V

            9: 0.787V
            10: 0.735V
            11: 0.867V
            12: 0.783V
            13: 0.369V

            14: 10.8mV
            15: 2.174V
            16: 0.708V
            17: 0.640V
            18: 0.754V
            19: 0.734V

            20: 0.867V
            21: 0.805V
            22: 0.627V
            23: 0.602V

            24: 0.692V
            25: 0.669V
            26: 0.797V

            All of these tests are via grounding to chassis with the TV on (backlghts going) and in the fault condition. I hope this is ok.

            Many thanks.
            Attached Files
            Last edited by rowage; 02-28-2020, 05:27 AM.

            Comment


              #7
              Re: Samsung UA40J5100 LED SMPS voltage

              It does look like it's the t-con at fault
              VCC 3.3V - nothing (1.1 to 1.3mV)
              VCC 1.8V - nothing (0.2mV)
              VCC 1.15V - nothing (0.1mV)
              I suspect thet could be a shorted mlcc (ceramic cap) likely on vcc1.8v. These caps don't realy like high humidity conditions like you have. Sometimes the bad cap will get warm so you might be able to find it by tiuching them with a finger. It could also be a shorted ic.

              Just as a check, disconnect both flat cables going from the t-con to the panel and then recheck the 3.3VCC, if it comes up then it could be a fault on the panel.
              Last edited by R_J; 02-28-2020, 11:35 AM.

              Comment


                #8
                Re: Samsung UA40J5100 LED SMPS voltage

                Check this maybe helpful:
                Attached Files
                Last edited by Robinsosa; 02-28-2020, 11:59 AM.

                Comment


                  #9
                  Re: Samsung UA40J5100 LED SMPS voltage

                  Hi RJ and Robinsosa,

                  I disconnected both cables to panel and tested VCC 3.3V - no change.

                  As per document that Robinsosa posted, no LED's light up on TCON except sometimes a brief flash from one of them on startup.

                  But fuse on TCON is not open so does that mean it is the LVDS cable or the TCON? I don't know if this is a no-no, but I reversed the LVDS cable and it made no difference either.

                  Thank you once again for your kind help.

                  Comment


                    #10
                    Re: Samsung UA40J5100 LED SMPS voltage

                    The LVDS cable (cable between main board and t-con) can't be reversed, it should only have contacts on one side. If you have the +12 volts to the t-con, you should have the other voltages, unless there is a tcon board problem. On the lvds cable, pins 1~5 have the +12v, the other pins on the lvds cable are for the video signal.

                    Comment


                      #11
                      Re: Samsung UA40J5100 LED SMPS voltage

                      Hi RJ, what I mean to say is that I took the end of the LVDS ribbon from the MAIN and plugged it into the TCON, then plugged the TCON end of the LVDS into the MAIN. So I didn't turn it upside down, I just reversed it. Contacts still all facing down onto the board contacts.

                      Likely a TCON fault then?

                      Thanks again.

                      Comment


                        #12
                        Re: Samsung UA40J5100 LED SMPS voltage

                        Looks like you have 12.7 on the first pin but the next 4 or so are too low, can you tell if you are getting those 12 volts from the mainboard, maybe carefully measure those pins with the connector unplugged.

                        Comment


                          #13
                          Re: Samsung UA40J5100 LED SMPS voltage

                          Those first 5 pins should all be connected together, You could recheck them, but I suspect it was just a poor meter probe contact, as long as there is 12 volts on both sides of the fuse, and low 3.3 etc, it is likely the t-con at fault.

                          Comment


                            #14
                            Re: Samsung UA40J5100 LED SMPS voltage

                            Hi RJ and nomoresonys. I tested the output pins on the MAIN as pictured. The first five inside the square I have drawn all read 12.7v with the LVDS connected. They rise to around 13v with the LVDS disconnected.

                            All the other pins in that line are 1.something volts. Mostly 1.2v.

                            The first five pins that I numbered on the TCON in the last pic, they are all reading the same as I last stated. Only the first one reads 12.7v. I confirmed the ground point each time I tested a pin by going back to both sides of the TCON fuse and checking for 12.7. Same thing every time.

                            Cheers. Oh, and if I make it off this island for a holiday any time, I will be sure to buy all of you a beer :-)
                            Attached Files
                            Last edited by rowage; 03-02-2020, 02:51 AM.

                            Comment


                              #15
                              Re: Samsung UA40J5100 LED SMPS voltage

                              Soooo, since the first five on the MAIN are all 12.7v, but only the first pin on the TCON is 12.7v, does that indicate a faulty LVDS cable? Or are we sticking with the TCON being faulty?

                              Many thanks.

                              Comment


                                #16
                                Re: Samsung UA40J5100 LED SMPS voltage

                                According to post #6 you are not checking the pins properly
                                Attached Files
                                Last edited by R_J; 03-03-2020, 03:21 PM.

                                Comment


                                  #17
                                  Re: Samsung UA40J5100 LED SMPS voltage

                                  Wow, ok thanks for that. I will try to check those pins but I am not sure I have the skills. If I touch two of the 12v pins together will I short anything out?

                                  Cheers.

                                  Comment


                                    #18
                                    Re: Samsung UA40J5100 LED SMPS voltage

                                    Don't worry about it. As long as you have the +12 volts on the T-con fuse, thats all that mattered. And you have that. They use 5 pins for the +12 volts to handle the current (2~3 amps) to supply the t-con AND panel. One small pin could not handle it.
                                    Last edited by R_J; 03-03-2020, 07:24 PM.

                                    Comment


                                      #19
                                      Re: Samsung UA40J5100 LED SMPS voltage

                                      OK thank you RJ. I presume the next step is to replace the TCON then?

                                      Comment


                                        #20
                                        Re: Samsung UA40J5100 LED SMPS voltage

                                        Originally posted by R_J View Post
                                        It does look like it's the t-con at fault
                                        I suspect thet could be a shorted mlcc (ceramic cap) likely on vcc1.8v. These caps don't realy like high humidity conditions like you have. Sometimes the bad cap will get warm so you might be able to find it by tiuching them with a finger. It could also be a shorted ic.

                                        Just as a check, disconnect both flat cables going from the t-con to the panel and then recheck the 3.3VCC, if it comes up then it could be a fault on the panel.
                                        Hi RJ,

                                        After over a year, the TCON I ordered finally arrived on our supply ship. I fitted it and the set is working fine. Thank you SO SO MUCH for your kind advice. When I find myself in Canada, I will look you up to buy you a beer.

                                        Thanks again.

                                        Comment

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