Looking for couple tips please

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  • ohmmy
    Senior Member
    • Jan 2013
    • 182
    • USA

    #21
    Re: Looking for couple tips please

    Great. If the psu has both a ps_on and backlight on pin, do both need to be triggered on with a resistor?

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #22
      Re: Looking for couple tips please

      Yes, each resistor for each signal pin, and sometime the Dimming pin also.
      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

      • ohmmy
        Senior Member
        • Jan 2013
        • 182
        • USA

        #23
        Re: Looking for couple tips please

        Could someone's briefly explain what voltages you normally look for on a t-con and what they do?

        Comment

        • tom66
          EVs Rule
          • Apr 2011
          • 32560
          • UK

          #24
          Re: Looking for couple tips please

          5V/12V/13V input typically
          Logic supply voltages: 1.2, 1.5, 1.8, 2.5, 3.3, 5V.
          Panel source driver voltage: AVDD (15~16V)
          Panel common voltage: VCOM (AVDD/2 or 7~8V)
          Panel gate driver voltages: VON/VGH (+20V to +35V) and VOFF/VGL (-5V to -10V)
          Gamma voltages are monotonic around VCOM.
          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

          • ohmmy
            Senior Member
            • Jan 2013
            • 182
            • USA

            #25
            Re: Looking for couple tips please

            Awesome Tom! Why are there negative voltages?

            Comment

            • tom66
              EVs Rule
              • Apr 2011
              • 32560
              • UK

              #26
              Re: Looking for couple tips please

              Ground is relative.

              The way I understand an LCD panel is that the negative voltages take the TFT pixel gate way past the bias point, making sure it stays off. The positive voltages turn the transistor (TFT) from off to conductive, the amount of conduction dependent on the voltage between gate and source.

              tl;dr: ground is relative.
              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

              • ohmmy
                Senior Member
                • Jan 2013
                • 182
                • USA

                #27
                Re: Looking for couple tips please

                Cool. I've read conflicting information about when light is passed through that the TFT is off (non conducting) and others have said that when light is passed through its on (conducting).

                Which is it?

                Comment

                • budm
                  Badcaps Legend
                  • Feb 2010
                  • 40746
                  • USA

                  #28
                  Re: Looking for couple tips please

                  Some info.
                  Attached Files
                  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

                  • ohmmy
                    Senior Member
                    • Jan 2013
                    • 182
                    • USA

                    #29
                    Re: Looking for couple tips please

                    Originally posted by tom66
                    5V/12V/13V input typically
                    Logic supply voltages: 1.2, 1.5, 1.8, 2.5, 3.3, 5V.
                    Panel source driver voltage: AVDD (15~16V)
                    Panel common voltage: VCOM (AVDD/2 or 7~8V)
                    Panel gate driver voltages: VON/VGH (+20V to +35V) and VOFF/VGL (-5V to -10V)
                    Gamma voltages are monotonic around VCOM.
                    Can you explain what all those labels mean in terms of tcon operation goes? Im only really aware of the low negative and positive signal voltages coming from LVDS cable

                    Comment

                    • tom66
                      EVs Rule
                      • Apr 2011
                      • 32560
                      • UK

                      #30
                      Re: Looking for couple tips please

                      VON/VGH is used to make a row on the panel take pixel information, VOFF/VGL is used to deselect it. The panel is updated rapidly and continuously. AVDD goes to the SOURCE drivers and controls the pixel intensity. Gamma voltages make the pixel colours look even and accurate. VCOM is used to avoid panel DC bias, leaving burned images. Poor VCOM causes violent visible strobe effect.
                      Last edited by tom66; 11-24-2013, 09:25 AM.
                      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

                      • randtek
                        Badcaps Veteran
                        • Oct 2011
                        • 280
                        • US

                        #31
                        Re: Looking for couple tips please

                        A quick tip about adjusting Vs and Va (and a good practice for most types of electronic adjustment)

                        You should always operate the TV for about 20 minutes to allow it to come to full, normal operating temperature before performing the adjustment. This allows for the most accurate adjustment.

                        Comment

                        • ohmmy
                          Senior Member
                          • Jan 2013
                          • 182
                          • USA

                          #32
                          Re: Looking for couple tips please

                          Awesome. Thanks for the info.

                          I'm curious, does running an LCD backlight at full intensity lessen the ccfls lifespan?

                          Comment

                          • tom66
                            EVs Rule
                            • Apr 2011
                            • 32560
                            • UK

                            #33
                            Re: Looking for couple tips please

                            Yes, but it's not worth worrying about. Typically 50,000 hrs can be achieved by most backlights.
                            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

                            • ohmmy
                              Senior Member
                              • Jan 2013
                              • 182
                              • USA

                              #34
                              Re: Looking for couple tips please

                              Hi guys, curious.. Why do some lcd tvs have master/slave inverters? Does each board drive different ccfls?

                              Comment

                              • ohmmy
                                Senior Member
                                • Jan 2013
                                • 182
                                • USA

                                #35
                                Re: Looking for couple tips please

                                Originally posted by ohmmy
                                Hi guys, curious.. Why do some lcd tvs have master/slave inverters? Does each board drive different ccfls?
                                Still wondering about this

                                Also I've been meaning to ask, what are all these solder lines over traces underneath power supplies? Are they a type of shielding? Thanks to anyone in advance!
                                Attached Files

                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA

                                  #36
                                  Re: Looking for couple tips please

                                  They are bare copper traces covered with solder so the trace can handle more current.
                                  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

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