Testing a Buffer Board LJ41-05121A

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  • speedypro
    Badcaps Veteran
    • Feb 2013
    • 561
    • United Kingdom

    #1

    Testing a Buffer Board LJ41-05121A

    I am seeing that the ICs are faulty on these boards (3407F). But how to test them? These boards are found in Samsung 50' plasma TV sets.
    Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer
  • Caleb
    Smokin IC's
    • Feb 2013
    • 645
    • USA

    #2
    Re: Testing a Buffer Board LJ41-05121A

    youtube on testing these
    Liberating magic smoke one part at a time

    Comment

    • speedypro
      Badcaps Veteran
      • Feb 2013
      • 561
      • United Kingdom

      #3
      Re: Testing a Buffer Board LJ41-05121A

      Originally posted by Caleb
      youtube on testing these
      Thanks! Found two ICs on my buffer board at fault
      Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer

      Comment

      • tw2005
        Badcaps Legend
        • Oct 2011
        • 6458
        • Australia

        #4
        Re: Testing a Buffer Board LJ41-05121A

        https://www.badcaps.net/forum/attach...7&d=1400500489

        Comment

        • speedypro
          Badcaps Veteran
          • Feb 2013
          • 561
          • United Kingdom

          #5
          Re: Testing a Buffer Board LJ41-05121A

          Full-time computer repair tech (10am - 6pm) and full-time, (8am - 11pm), Ruby on Rails Developer

          Comment

          • tw2005
            Badcaps Legend
            • Oct 2011
            • 6458
            • Australia

            #6
            Re: Testing a Buffer Board LJ41-05121A

            Comment

            • st.jimmy05
              Member
              • May 2015
              • 17
              • united kingdom

              #7
              Re: Testing a Buffer Board LJ41-05121A

              Hi there, Got the buffer boards and Y-MAIN board from Samsung 50" HD

              LJ41-05120A
              R1.3

              Buffers LJ-05121A & 22A with R1.0

              Fluke 115 set to diode RED to input between 1-24 and BLACK along OP's with no continuous bleep? at least one obvious totally blown IC U5401 on board 121A and obvious damage to Y-MAIN with blown caps, one cap so bad i could not ID it but board REF is C5817 if anyone can ID it. next obvious is C5807.

              Im no pro, started trying to ment a small 22" for my daughter, friend mentioned his went off with a bit of smoke and a quote to repair, offered to help as best i could.. but really want to make sure i can replace all faults before purchasing any components etc. hope all pictures help.
              Attached Files

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              • Caleb
                Smokin IC's
                • Feb 2013
                • 645
                • USA

                #8
                Re: Testing a Buffer Board LJ41-05121A

                Buffers will require lots of practice to remove and replace without damaging the board. Also a hot air station will likely be required. I am not familiar with the common mode for failure of this ysus, but a repair kit lists Q5500, Q5501, Q5302, Q5303, Q5304, Q5306, as well as 2 surface mount resistors, 3 capacitors, 1 zener diode, buffer chip is IC 3407F. However that cap that is blown to pieces is not one of the common ones to fail so your board is likely in worse shape than the normal failure
                Liberating magic smoke one part at a time

                Comment

                • tw2005
                  Badcaps Legend
                  • Oct 2011
                  • 6458
                  • Australia

                  #9
                  Re: Testing a Buffer Board LJ41-05121A

                  Originally posted by st.jimmy05
                  Hi there, Got the buffer boards and Y-MAIN board from Samsung 50" HD

                  LJ41-05120A
                  R1.3

                  Buffers LJ-05121A & 22A with R1.0

                  Fluke 115 set to diode RED to input between 1-24 and BLACK along OP's with no continuous bleep? at least one obvious totally blown IC U5401 on board 121A and obvious damage to Y-MAIN with blown caps, one cap so bad i could not ID it but board REF is C5817 if anyone can ID it. next obvious is C5807.

                  Im no pro, started trying to ment a small 22" for my daughter, friend mentioned his went off with a bit of smoke and a quote to repair, offered to help as best i could.. but really want to make sure i can replace all faults before purchasing any components etc. hope all pictures help.
                  that's pretty messed up ymain. you may have trouble with that buffer looking at that burn. I've got one like that and it's burnt through the board and tracks making it not repairable.

                  Comment

                  • st.jimmy05
                    Member
                    • May 2015
                    • 17
                    • united kingdom

                    #10
                    Re: Testing a Buffer Board LJ41-05121A

                    thanks, i had thought the same in relation to the damage, as it's not the common failure.

                    paul

                    Comment

                    • st.jimmy05
                      Member
                      • May 2015
                      • 17
                      • united kingdom

                      #11
                      Re: Testing a Buffer Board LJ41-05121A

                      Originally posted by tw2005
                      that's pretty messed up ymain. you may have trouble with that buffer looking at that burn. I've got one like that and it's burnt through the board and tracks making it not repairable.

                      Yeah, pretty nasty isn't it, this was my first thought when i seen the buffer IC that it has probably burned through the tracks on the board.. very unfortunate has been quite a failure to cause that damage to the boards, so put it down to a write off lol.

                      thanks

                      Comment

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