Announcement

Collapse
No announcement yet.

Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #21
    Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

    BTW, when you removed that MOSFET on the heatsink, that MOSFET is for PFC Voltage booster, when you put it back are you getting 380 ~ 400VDC Voltage (measure between the legs of the cap) on the main 450VDC filter cap legs?
    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


      #22
      Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

      Originally posted by budm View Post
      BTW, when you removed that MOSFET on the heatsink, that MOSFET is for PFC Voltage booster, when you put it back are you getting 380 ~ 400VDC Voltage (measure between the legs of the cap) on the main 450VDC filter cap legs?
      I did not do any voltage measurements with that mosfet removed, I just checked it for shorts and removed it to identify it....it was mounted funny; face down. The only way to identify it was to desolder it. If you want measurements with it removed, I surely can.
      <--- Badcaps.net Founder

      Badcaps.net Services:

      Motherboard Repair Services

      ----------------------------------------------
      Badcaps.net Forum Members Folding Team
      http://folding.stanford.edu/
      Team : 49813
      Join in!!
      Team Stats

      Comment


        #23
        Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

        What I mean is that after you solder it back into the board, is the PFC Boost Voltage still present or not.
        BTW, I also forget to ask if the 3.3V is going up and down when you run the power supply board by itself or not without anything connected it but just AC cord.
        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


          #24
          Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

          Originally posted by budm View Post
          BTW, I also forget to ask if the 3.3V is going up and down when you run the power supply board by itself or not without anything connected it but just AC cord.
          Yes, it does... in sync with the faint 'chirp' I hear that's also in time with the blinking STBY/Power LED...
          <--- Badcaps.net Founder

          Badcaps.net Services:

          Motherboard Repair Services

          ----------------------------------------------
          Badcaps.net Forum Members Folding Team
          http://folding.stanford.edu/
          Team : 49813
          Join in!!
          Team Stats

          Comment


            #25
            Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

            can you pin point where the chirp is from?
            Since the 14V standby power supply is stable, there must be the problem some where in the step down power supplies/loads that is going on and off.
            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


              #26
              Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

              What are the numbers on IC9101, I see voltage test points around it, like A_12v (always 12 volts) Is the A12V stable? I suspect the A_12V supplies other ldo's. I see what look like many ldo regulators in the picture with the heat sink removed.
              Last edited by R_J; 05-01-2021, 06:39 PM.

              Comment


                #27
                Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

                Sorry for the delay, fellas.....I had to slide this aside to work on some other stuff....but I've got this one back on the bench.

                Originally posted by budm View Post
                can you pin point where the chirp is from?
                Since the 14V standby power supply is stable, there must be the problem some where in the step down power supplies/loads that is going on and off.
                With the naked ear, no....it's very faint. I need to find my old stethoscope....it got lost in the garage (also good for finding boost leaks and vacuum hissing in cars).

                Originally posted by R_J View Post
                What are the numbers on IC9101, I see voltage test points around it, like A_12v (always 12 volts) Is the A12V stable? I suspect the A_12V supplies other ldo's. I see what look like many ldo regulators in the picture with the heat sink removed.
                It's marked:

                Line 1: SLM4281A
                Line 2: 1833
                <--- Badcaps.net Founder

                Badcaps.net Services:

                Motherboard Repair Services

                ----------------------------------------------
                Badcaps.net Forum Members Folding Team
                http://folding.stanford.edu/
                Team : 49813
                Join in!!
                Team Stats

                Comment


                  #28
                  Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

                  IC9101 has no datasheet, so I don't know if it has anything to do with the voltages in that area. You said the 14 volts is stable, did you check if any of the other sub voltages are also stable ie: A_12V

                  Comment


                    #29
                    Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

                    Originally posted by R_J View Post
                    IC9101 has no datasheet, so I don't know if it has anything to do with the voltages in that area. You said the 14 volts is stable, did you check if any of the other sub voltages are also stable ie: A_12V
                    There is 12.5~12.9v there, drops/fluctuates ~.5v with the 'chirp'. With the aid of a stethoscope, the 'chirp' seems to be coming from TP801CS....but it's very faint, so I can't guarantee that....but that's where it was the loudest.

                    https://www.badcaps.net/forum/attach...1&d=1620847524
                    Attached Files
                    <--- Badcaps.net Founder

                    Badcaps.net Services:

                    Motherboard Repair Services

                    ----------------------------------------------
                    Badcaps.net Forum Members Folding Team
                    http://folding.stanford.edu/
                    Team : 49813
                    Join in!!
                    Team Stats

                    Comment


                      #30
                      Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

                      Originally posted by Topcat View Post
                      It's marked:

                      Line 1: SLM4281A
                      Line 2: 1833
                      How many pins are there on that IC ?
                      All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

                      Comment


                        #31
                        Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

                        Originally posted by smdflea View Post
                        how many pins are there on that ic ?
                        16.
                        <--- Badcaps.net Founder

                        Badcaps.net Services:

                        Motherboard Repair Services

                        ----------------------------------------------
                        Badcaps.net Forum Members Folding Team
                        http://folding.stanford.edu/
                        Team : 49813
                        Join in!!
                        Team Stats

                        Comment


                          #32
                          Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

                          Originally posted by Topcat View Post
                          16.
                          Samsung use renamed Magnachip parts afaik, it could be a MAP3249 ,its the only 4-channel LED 16 pin IC listed on their site: https://cdn.badcaps-static.com/pdfs/...74f7b75b74.pdf

                          .
                          Last edited by SMDFlea; 05-15-2021, 01:03 PM.
                          All donations to badcaps are welcome, click on this link to donate. Thanks to all supporters

                          Comment


                            #33
                            Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

                            Hello Topcat , did you ever do any good with this samsung ? I have the exact tv with same issues . thank you

                            Comment


                              #34
                              Re: Samsung UN43NU6900FXZA 43" 4K - Power Supply Issue

                              Originally posted by basementtech View Post
                              Hello Topcat , did you ever do any good with this samsung ? I have the exact tv with same issues . thank you
                              No, I never did figure it out. I reassembled it and shelfed it hoping maybe I'd encounter one someday with a broken screen but a good board. It must be a common problem, there are no used boards anywhere for this thing.
                              <--- Badcaps.net Founder

                              Badcaps.net Services:

                              Motherboard Repair Services

                              ----------------------------------------------
                              Badcaps.net Forum Members Folding Team
                              http://folding.stanford.edu/
                              Team : 49813
                              Join in!!
                              Team Stats

                              Comment


                                #35
                                Good day:

                                I am looking for a Service manual and schematic for this same model TV (UN43NU6900FXZA). I also have a power supply issue. No standby light, the fuse on the board is good, and about 170 volts is getting to the MOSFET (60R360QS), that same 170 Volts (DC) is at the transformer. I removed the MOSFET and tested it and other than having a high RDS of .7 ohms, ( I can't find a exact match datasheet for the MOSFET). I can only find a datasheet for a 60R360Q., that datasheet calls for an RDS of .36. I think it maybe OK? Oh and also the TV is about 5 years old and I noticed maybe after about a year of use the TV would go blank for a few seconds every now and again and then come back on in a second or two or three (Now the TV is dead). Any help would great.

                                Thanks

                                Comment


                                  #36
                                  [QUOTE=Protractor_4transisters;n3166147]Good day:

                                  I am looking for a Service manual and schematic for this same model TV (UN43NU6900FXZA). I also have a power supply issue. No standby light, the fuse on the board is good, and about 170 volts is getting to the MOSFET (60R360QS), that same 170 Volts (DC) is at the transformer. I removed the MOSFET and tested it and other than having a high RDS of .7 ohms, ( I can't find a exact match datasheet for the MOSFET). I can only find a datasheet for a 60R360Q., that datasheet calls for an RDS of .36. I think it maybe OK? Oh and also the TV is about 5 years old and I noticed maybe after about a year of use the TV would go blank for a few seconds every now and again and then come back on in a second or two or three (Now the TV is dead). Any help would great.

                                  I would check the solder joints on the powerboard and the electrolytic capacitors.

                                  Comment


                                    #37
                                    Originally posted by nomoresonys View Post

                                    I would check the solder joints on the powerboard and the electrolytic capacitors.
                                    I have tested all the capacitors (in-circuit) they all test (and look) good. I have not tested the ESR of the caps. though. Maybe I should just recap. the power section of the board? Any thoughts on that.

                                    Comment


                                      #38
                                      That would eliminate them as suspects.

                                      Comment


                                        #39
                                        Originally posted by Protractor_4transisters View Post

                                        I have tested all the capacitors (in-circuit) they all test (and look) good. I have not tested the ESR of the caps. though. Maybe I should just recap. the power section of the board? Any thoughts on that.
                                        FWIW, I checked all those caps on my LCR. They were fine.
                                        <--- Badcaps.net Founder

                                        Badcaps.net Services:

                                        Motherboard Repair Services

                                        ----------------------------------------------
                                        Badcaps.net Forum Members Folding Team
                                        http://folding.stanford.edu/
                                        Team : 49813
                                        Join in!!
                                        Team Stats

                                        Comment

                                        Working...
                                        X