Samsung 50" plasma blank screen

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  • Tweek4
    Member
    • Feb 2012
    • 45

    #61
    Re: Samsung 50" plasma blank screen

    I don't have a scope. Just a DMM and soldering iron.
    I'll spend some time on it this weekend.
    Peter

    Comment

    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK

      #62
      Re: Samsung 50" plasma blank screen

      Check the vertical drive voltage is present. Should be around 60V and is labelled Va. It may be coming out of PSU but is it arriving on F board?
      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

      Comment

      • Tweek4
        Member
        • Feb 2012
        • 45

        #63
        Re: Samsung 50" plasma blank screen

        Tom66...
        My tv differs somewhat from the manual I have been referring to.
        The power to buffers E and F come through the Y main board on my tv.
        Here's what I found.
        Va at the test point = 56v. Vs=205v
        Va leaving smps board to Y main= 48v(CN810)
        Vs leaving smps board to y main= 182v
        Va at the Y main socket end was different every time I measured it. From 80v to 240v. Vs at the same socket was 170v. Double and triple checked.
        Va to E buffer= 56v.
        E to F buffers = 5v, 8v and 8v(3 wire jumper).
        Strange Va?????
        Peter

        Comment

        • tom66
          EVs Rule
          • Apr 2011
          • 32560
          • UK

          #64
          Re: Samsung 50" plasma blank screen

          That is strange - is the voltage disappearing across the board? I don't quite understand the readouts.
          Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
          For service manual, schematic, boardview (board view), datasheet, cad - use our search.

          Comment

          • Tweek4
            Member
            • Feb 2012
            • 45

            #65
            Re: Samsung 50" plasma blank screen

            I just checked again.
            Voltage measured on the smps going to X board: Vs=206v, Va= 56v
            Going to Y board: Vs=182, Va=48v
            If I unplug Y board connector, Vs=190v, Va = 52v
            Still looking
            Peter

            Comment

            • Tweek4
              Member
              • Feb 2012
              • 45

              #66
              Re: Samsung 50" plasma blank screen

              Further check:
              with y and x boards disconnected from the smps, ref Vs=206, Va=56, Vs@x board connector=206, Vs and Va at y board connector=190 and 51.
              With x board reconnected, Vs and Va no change.
              With both x and y boards reconnected, Vs andVa to y board drop to 186 and 48. Vs to x board no change.
              Seems like the smps board is not regulating properly.
              Any component checks or replace the smps board?
              Peter

              Comment

              • tom66
                EVs Rule
                • Apr 2011
                • 32560
                • UK

                #67
                Re: Samsung 50" plasma blank screen

                Originally posted by Tweek4
                Further check:
                with y and x boards disconnected from the smps, ref Vs=206, Va=56, Vs@x board connector=206, Vs and Va at y board connector=190 and 51.
                With x board reconnected, Vs and Va no change.
                With both x and y boards reconnected, Vs andVa to y board drop to 186 and 48. Vs to x board no change.
                Seems like the smps board is not regulating properly.
                Any component checks or replace the smps board?
                Peter
                I think if the SMPS was not regulating, you would get a dim picture. It might rise under no load, but that is to be expected.

                I think you main board or logic board is faulty but can't think of a test to prove it. Someone else on these forums has the same problem with an LG plasma. The only way to really check it would be with a scope.
                Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                Comment

                • Tweek4
                  Member
                  • Feb 2012
                  • 45

                  #68
                  Re: Samsung 50" plasma blank screen

                  I already tried another logic board- no change.
                  I think I will swap the main board then.
                  Thanks, tom66
                  Peter

                  Comment

                  • Tweek4
                    Member
                    • Feb 2012
                    • 45

                    #69
                    Re: Samsung 50" plasma blank screen

                    Well- I just received and installed the main board. No change.
                    Vs and Va voltages are the same as previously measured.
                    Maybe the SMPS board?

                    Peter

                    Comment

                    • tom66
                      EVs Rule
                      • Apr 2011
                      • 32560
                      • UK

                      #70
                      Re: Samsung 50" plasma blank screen

                      Originally posted by Tweek4
                      Well- I just received and installed the main board. No change.
                      Vs and Va voltages are the same as previously measured.
                      Maybe the SMPS board?

                      Peter
                      Which main board - the one with the inputs?
                      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                      Comment

                      • Tweek4
                        Member
                        • Feb 2012
                        • 45

                        #71
                        Re: Samsung 50" plasma blank screen

                        yes
                        Previously I tried a different logic board.

                        Comment

                        • tom66
                          EVs Rule
                          • Apr 2011
                          • 32560
                          • UK

                          #72
                          Re: Samsung 50" plasma blank screen

                          Originally posted by Tweek4
                          yes
                          Previously I tried a different logic board.
                          I'm drawing a blank now, I wish I could help. Someone discovered this was a Y-sustain fault on an LG, but they haven't replaced it yet so we can't be sure.
                          Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
                          For service manual, schematic, boardview (board view), datasheet, cad - use our search.

                          Comment

                          • Tweek4
                            Member
                            • Feb 2012
                            • 45

                            #73
                            Re: Samsung 50" plasma blank screen

                            Thanks for the help, Tom66.
                            I still have a hard time believing that this tv, having very few hours on it and zero problems, failed by just moving it 20 feet.
                            I'll keep an eye on the forum for ideas.
                            Thanks again
                            Peter

                            Comment

                            • Tweek4
                              Member
                              • Feb 2012
                              • 45

                              #74
                              Re: Samsung 50" plasma blank screen

                              I received a letter from Samsung last week indicating that my tv might qualify for a specific repair under a class action suit proposed settlement brought against Samsung. The suit cites a capacitor failure on the power supply board, I believe and to cut a long story short, the repair guru arrived today and checked the suspect capacitor which turned out to be OK. Installed a new power supply board anyway. He also found a couple of bulging caps on the Y sustain board, did voltage checks, and after close inspection of the display panel found a couple of tiny pots in the lower right corner and declared that the panel is bad. Not worth the expense to fix.
                              No more plasma tv for me.
                              Peter

                              Comment

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