RCA RLC3708A No Backlight Adjustment.

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  • Doug
    New Member
    • Oct 2010
    • 8
    #1

    RCA RLC3708A No Backlight Adjustment.

    Pressing "Input 2580" on the aftermarket remote opens the service menu.
    I navigate to: "Other Setting" - "BackLight Adjustment"
    The numerical scale goes from Zero to 100.
    I have tried many different settings using the setup and service menus.
    This (ccfl) LCD has good picture and all other settings are adjustable.
    A factory reset defaults the backlight setting to 80.
    The BackLight Adjustment setting does nothing.
    The picture is almost too dark to watch.
    This TV was built in March of 2012.
    This model is also branded as Curtis, Proscan and maybe others.
    Attached Files
    Last edited by Doug; 01-02-2015, 10:04 AM.
    Tags: None
    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK
      #2
      Re: RCA RLC3708A No Backlight Adjustment.

      You should check the BL ADJ or DIM or BRI pin on the inverter board, see if the voltage on it changes as you adust the backlight control on the user menu. Usually it ranges from around 0-0.3V (minimum) to about 2.5-3.3V (maximum)
      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

        • Doug
          New Member
          • Oct 2010
          • 8
          #3
          Re: RCA RLC3708A No Backlight Adjustment.

          I checked the DIM pin on the inverter board,the voltage on this pin did not change as i adjusted the BackLight control with the user menu. The voltage on the DIM pin did not fluctuate from .3V (minimum).
          I applied .6V to the DIM pin on the inverter IC using an almost dead coin battery and the backlight brightened instantly.
          Thanks so much to tom66.
          He nailed this perfectly.
          Attached Files
          Last edited by Doug; 01-05-2015, 11:36 PM.

            Comment

            • budm
              Badcaps Legend
              • Feb 2010
              • 40746
              • USA
              #4
              Re: RCA RLC3708A No Backlight Adjustment.

              Did you find out if it uses PWM DIMMING (FREQ around 200Hz, 10% pulse width = min, 90% pulse width = max brightness) or if it uses Analog dimming?
              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

                • Doug
                  New Member
                  • Oct 2010
                  • 8
                  #5
                  Re: RCA RLC3708A No Backlight Adjustment.

                  No, I did not find out if it uses PWM dimming or Analog dimming.
                  I have soldered a small wire to the DIM pin.
                  Applying about .9V -1V to the DIM pin brightens the image nicely.
                  This TV has been on for about 30 hours since this work-around.
                  Thanks again!
                  Attached Files

                    Comment

                    • budm
                      Badcaps Legend
                      • Feb 2010
                      • 40746
                      • USA
                      #6
                      Re: RCA RLC3708A No Backlight Adjustment.

                      If you remove the DIM control wire feeding the Inverter board, if it is PWM on that control wire, the backlights should then be at full brightness, if it is analog on that control wire, then the backlights will be off.
                      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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