Panasonic TH-42Z700U Buffer or Panel that is the question!

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  • Shinju
    Badcaps Legend
    • Mar 2014
    • 1239
    • USA
    #1

    Panasonic TH-42Z700U Buffer or Panel that is the question!

    Hey friends of the BCF!

    I got this little 42 inch here and when turned on it looks like 75% of the screen is void.

    AS you can see the OSD is cut off but when a signal source is connected the screen is 100% with a 3" sort of transparent green line going half way as you can see in other pictures.

    When the screen transitions to black it cuts out a large chuck only going halfway. This leads me to believe its a bad buffer.

    NOW to the even more obscure affliction.

    The picture setting is at full, when I go to adjust it down the screen starts to go negative and when I get to -3 it starts to strobe. Could this be cause by the problematic buffer or is this a SC board about to go boom?

    I tried to get video of it but the camera wouldn't show the flicker so that didn't work.

    Other then that the panel seems to be fine and the Green line only shows up when there is a signal.

    No gut shots yet, I just got to this after fixing a couple of panels before hand and I wanted to save my back from the 1000 screws Panasonic likes to use to button up their units!

    Scrap or fixable!?
    Attached Files
    Last edited by Shinju; 11-03-2014, 11:58 AM.
    Tags: None
    • Alastair E
      Chief Womble
      • Mar 2013
      • 1963
      • U.K.
      #2
      Re: Panasonic TH-42Z700U Buffer or Panel that is the question!

      The PZ70 series has buffers top and bottom.

      Looks like theres an issue with that buffer/COF chip that drives that section of screen....

      Unlike more usual sets, this is Panasonic's first FHD 42" set and the upper and lower address buffers only drive the screen to halfway down, not all the way vertically.....
      TELEFIX

      How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
      http://www.irf.com/technical-info/appnotes/an-1088.pdf
      PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

        Comment

        • Shinju
          Badcaps Legend
          • Mar 2014
          • 1239
          • USA
          #3
          Re: Panasonic TH-42Z700U Buffer or Panel that is the question!

          I will break it down tonight and see about getting some voltages, I don't have a stand for it so it will have to lay face down!

          From the looks of things, parts are pretty cheap.

            Comment

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK
              #4
              Re: Panasonic TH-42Z700U Buffer or Panel that is the question!

              Looks to me like the address COF has a loose connection, probably fixable by reseating or cleaning the connector.
              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

                • Shinju
                  Badcaps Legend
                  • Mar 2014
                  • 1239
                  • USA
                  #5
                  Re: Panasonic TH-42Z700U Buffer or Panel that is the question!

                  Would that loose connection account for the screen strobing when adjusting the picture setting?

                    Comment

                    • tom66
                      EVs Rule
                      • Apr 2011
                      • 32560
                      • UK
                      #6
                      Re: Panasonic TH-42Z700U Buffer or Panel that is the question!

                      Er... that's an interesting one. Can you get a video of that?
                      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

                        • Shinju
                          Badcaps Legend
                          • Mar 2014
                          • 1239
                          • USA
                          #7
                          Re: Panasonic TH-42Z700U Buffer or Panel that is the question!

                          I tried, the video didn't pick it up! all is shows is a normal looking screen. I might see if I can do a time laps to slow down the video as its filming.

                            Comment

                            • Shinju
                              Badcaps Legend
                              • Mar 2014
                              • 1239
                              • USA
                              #8
                              Re: Panasonic TH-42Z700U Buffer or Panel that is the question!

                              Fixed, details and gut photos later for future reference!

                                Comment

                                • Shinju
                                  Badcaps Legend
                                  • Mar 2014
                                  • 1239
                                  • USA
                                  #9
                                  Re: Panasonic TH-42Z700U Buffer or Panel that is the question!

                                  Hey all!

                                  It ended up being a dirty cable from the panel to the buffer (it always seems to be one that's under a fan!)

                                  I removed it cleaned it and the connector and popped it back in and voilà it fired right up and working. No more screen strobing or flicker.

                                  I did managed to snap a ribbon lock on the upper left buffer for the LDVS, it pretty much disintegrated as I was flipping it up. I managed to lock the cable down with what remained but so far its been working 100% as the cable was in there pretty damn tight with out being locked down.

                                  Panel was on for 8+ hours after the ribbon reseat and no issues thus far!

                                  Another Panny saved from the landfill!

                                  Now on to the next!
                                  Attached Files

                                    Comment

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