Sharp LC 46D64U Screen flashes then dies

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  • Bob Kontak
    Member
    • Dec 2013
    • 25
    • USA

    #1

    Sharp LC 46D64U Screen flashes then dies

    First post here. Howdy all.

    You may want to skip to the highlighted "Post Rambling" section. Perhaps less is more.

    Initial symptom - no action but constant 1 second interval of blinking green power light.

    Found reset sequence and green power light was constant for maybe 10 seconds then set would "click" off. However, before dying, screen would flash about 6-8 times. Fairly uniform.

    Disconnected 60V/12 V power leads to the inverter boards and using reset power would stay on. Hit the on/off button, set would shut down in a controlled manner and start back up when the on/off button was depressed. By start back up I mean the two red lights on the main board would flash.

    When reset and on, I plugged the right side inverter boards in at the inverter board (three wires from the main power board) and a flash at the connector was seen and instant shut down. Repeated routine for left side (right side disconnected) and same.

    Pulled inverter boards, farted around in full layman style with an ohm meter and found nothing weird.
    - mosfet thingies (noob here) were all consistent when 4 legs were tested among each other. Two of the four connectors had full continuity, let's say #1 and #3. No other hint of internal breakdown. All were consistent.

    - Transformers were all consistent. Around 190 ohms.

    - Single fuse on each side - top inverter board - had continuity.

    - Resistance among all board lamp contacts was the same - 3080 ohms - unless I tested a pair that were associated with a single transformer. Then resistance was 190.

    Put boards back on but left them unconnected from lamps. Plugged in, all is good (main board two flashing lights) Pushed inverter boards onto lamp connectors after five minutes and nothing happens. It does not die but no flashing screen.

    POST RAMBLING

    Turn set off and back on and lamp flickering pattern is completely different after removing and re-installing inverter boards. Example - Stays on for a few seconds, blinks a few times, stays on for five seconds, then stops. No circuit breaker hard shut off. Turn off then turn on, different sequence of flashes. One time went thru a flashing set and sustained (five second) on, stopped and then came back to life for another one or two sustained multi second attempts to stay lit.

    I do see six horizontal bars of light with an information box in upper right hand corner. Set has 22 connectors for lamps on each side. It is never as bright as when working properly.

    Caps are not puffy.

    Direction? Lamps?
    Attached Files
  • Bob Kontak
    Member
    • Dec 2013
    • 25
    • USA

    #2
    Re: Sharp LC 46D64U Screen flashes then dies

    Where's the love?

    Comment

    • Bob Kontak
      Member
      • Dec 2013
      • 25
      • USA

      #3
      Re: Sharp LC 46D64U Screen flashes then dies

      OK - Plugged in a DVD and I have audio and you can see the video just fine when the bulbs try to start. On average about a dozen bulb flickers then screen goes dark but audio remains. If I do this when the tv has sat unplugged for ten minutes, it will shut off after ten seconds. I do not have to reset it. I just turn it back on and it goes thru the same routine but does not shut itself off.

      Bulbs appear to be ok.

      Thoughts?

      Comment

      • tom66
        EVs Rule
        • Apr 2011
        • 32560
        • UK

        #4
        Re: Sharp LC 46D64U Screen flashes then dies

        60V stable to inverters during flickering?
        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

        • Bob Kontak
          Member
          • Dec 2013
          • 25
          • USA

          #5
          Re: Sharp LC 46D64U Screen flashes then dies

          Originally posted by tom66
          60V stable to inverters during flickering?
          Thank you. Will get back ASAP.

          Comment

          • Bob Kontak
            Member
            • Dec 2013
            • 25
            • USA

            #6
            Re: Sharp LC 46D64U Screen flashes then dies

            60 volts steady before flickering. During flickering a range of 59.1 to 60.3.

            Comment

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK

              #7
              Re: Sharp LC 46D64U Screen flashes then dies

              OK, and 12V? BL ON/OFF steady or not?
              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

              • Bob Kontak
                Member
                • Dec 2013
                • 25
                • USA

                #8
                Re: Sharp LC 46D64U Screen flashes then dies

                Drops a couple hundredths of a volt when flickering but baseline is 11.67.

                Comment

                • tom66
                  EVs Rule
                  • Apr 2011
                  • 32560
                  • UK

                  #9
                  Re: Sharp LC 46D64U Screen flashes then dies

                  That sounds OK so what about BL ON/OFF? Or some other on/off signal like: INV ON/OFF, INV POWER, BL ON, ON/OFF, etc, it will go to the master inverter in most cases.
                  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

                  • Bob Kontak
                    Member
                    • Dec 2013
                    • 25
                    • USA

                    #10
                    Re: Sharp LC 46D64U Screen flashes then dies

                    Ok - I believe BL means black? I think I am understanding you.

                    The number one inverter board has an input from the main board. The others don't. Plus number one is larger and has a few more gizmos on it than the other three.

                    So you want me to check the black line voltage (from main board) that feeds the master board and then the black line that feeds the slave board from the master for voltage fluctuation or anomolies?

                    Otherwise advise.

                    Many thanks. Will report back in a few.

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA

                      #11
                      Re: Sharp LC 46D64U Screen flashes then dies

                      BL = Backlights (most of the time they will use BL_ON, or INVR_ON, ON/OFF), in this case it is the Backlights ON/OFF signal which is generated by the main board.
                      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

                      • Bob Kontak
                        Member
                        • Dec 2013
                        • 25
                        • USA

                        #12
                        Re: Sharp LC 46D64U Screen flashes then dies

                        Outstanding.

                        Let me get my reading glasses on, pop a beer and get to business.

                        Edit: Slow going is ok, right?

                        Comment

                        • tom66
                          EVs Rule
                          • Apr 2011
                          • 32560
                          • UK

                          #13
                          Re: Sharp LC 46D64U Screen flashes then dies

                          Alcohol and high voltage isn't the greatest combination...
                          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

                          • Bob Kontak
                            Member
                            • Dec 2013
                            • 25
                            • USA

                            #14
                            Re: Sharp LC 46D64U Screen flashes then dies

                            No argument there. "A" beer is the key, for me at least. Three beers and I may change out antifreeze in a car. Three beers, I don't repair brakes. Old enough and have learned the hard way.

                            There is one cluster of wires that lead to the master inverter board from the main board. Four wires in total. One black, three grey.

                            The black wire and one of the grey wires feed 3.28 V to the inverter board. When I press the primary on/off button to on (with the DVD player on and playing), It takes a few seconds to spool up the voltage, but once hitting the 3.28 V, I can hear the audio and the screen flashes with DVD video observable.

                            It is steady once the 3.28 is achieved.

                            Edit: Please advise of add'l pics you may require. I am thankful for your help.
                            Attached Files
                            Last edited by Bob Kontak; 12-05-2013, 06:55 PM.

                            Comment

                            • Bob Kontak
                              Member
                              • Dec 2013
                              • 25
                              • USA

                              #15
                              Re: Sharp LC 46D64U Screen flashes then dies

                              Originally posted by budm
                              BL = Backlights (most of the time they will use BL_ON, or INVR_ON, ON/OFF), in this case it is the Backlights ON/OFF signal which is generated by the main board.
                              I am assuming the two wires that I found voltage from the main board to the master inverter are the what turn the backlights on.

                              Would there be an indication on the main board of what BL on/off is?

                              Of the four wires (main to inverter), one grounds to the case, two have voltage, and the fourth, I find no voltage or ground.

                              Comment

                              • Bob Kontak
                                Member
                                • Dec 2013
                                • 25
                                • USA

                                #16
                                Re: Sharp LC 46D64U Screen flashes then dies

                                There are letters "LB" on main board is this BL?
                                Attached Files

                                Comment

                                • Bob Kontak
                                  Member
                                  • Dec 2013
                                  • 25
                                  • USA

                                  #17
                                  Re: Sharp LC 46D64U Screen flashes then dies

                                  Anybody?

                                  Comment

                                  • johnboy1313
                                    Badcaps Legend
                                    • Nov 2012
                                    • 1959
                                    • USA

                                    #18
                                    Re: Sharp LC 46D64U Screen flashes then dies

                                    It looks like LB is the connector designation.

                                    Comment

                                    • vinceroger69
                                      Badcaps Legend
                                      • Mar 2012
                                      • 6714
                                      • uk

                                      #19
                                      Re: Sharp LC 46D64U Screen flashes then dies

                                      have you got the service manual for your model would help a lot if you can find one online etc

                                      Comment

                                      • Bob Kontak
                                        Member
                                        • Dec 2013
                                        • 25
                                        • USA

                                        #20
                                        Re: Sharp LC 46D64U Screen flashes then dies

                                        From main power board there is one set of wires that feeds the left set of inverters and one set of wires that feed the right set of inverters.

                                        Their voltage appears to be ok.

                                        From the separate main control board, The LB connector mentioned, two wires of four feed 3.28V to the master inverter board. Is this enough power? Is there a minimum it requires? If so, say 12v, I need to look upstream vs downstream.

                                        Comment

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