Sony bravia kdl 46nx700 dim screen issue

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  • jimbo-bob
    New Member
    • Feb 2021
    • 2
    • Australia

    #1

    Sony bravia kdl 46nx700 dim screen issue

    Hi everyone,

    I have a Sony bravia kdl 46nx700. It turns on, but the screen is awfully dim.
    Things I have tried:
    Went into settings and increased the brightness and contrast. Screen did not change at all.
    Went into settings and made sure any auto brightness settings and limit is turned off. Did not see any difference again even after playing with brightness and contrast.
    Did a factory reset. Again no change. Then repeated the steps above. No change.
    At this point I think with myself that this is a hardware problem. Since my tv does not have any warranty, I decide to open it up and have a look:
    There are no signs of blown capacitors or resistors or diods etc.
    I decided to measure the voltages on the pins going out to TCON board and the motherboard from the power board:
    When the tv is on (image on screen):

    TCON-ON 3.3V
    TCON VCC 12V 12.64V
    DIMMER-DC 3.31V
    DIMMER 1.659V
    BL-ON 3.05V
    BL-ERR 2.4mV
    REG12V 12.66V
    REG12V 12.66V
    REG12V-GND 7mV
    REG12V-GND 7mV
    AUDIO12V-GND 10.8mV
    AUDIO12V 12.7V
    POWER-ON 3.29V
    AC OFF-DET 3.34V
    STBY 3.3 3.34V

    When tv is off (power button is pressed and there is no image on screen):

    TCON-ON 0
    TCON VCC 12V 1mV
    DIMMER-DC 4.7mV
    DIMMER 4.9mV
    BL-ON 3.1mV
    BL-ERR 5.3mV
    REG12V 12.69V
    REG12V 12.69V
    REG12V-GND 3.6mV
    REG12V-GND 3.6mV
    AUDIO12V-GND 5.6mV
    AUDIO12V 12.71V
    POWER-ON 3.3V
    AC OFF-DET 3.35V
    STBY 3.3 3.35V

    So my questions are:

    Where does one find the voltage rating info for these pins? I came across manuals, but they only has schematics with no voltage info.
    I am bit suspicious about the DIM pin having ~ 1.7V. Is that meant to be the case?
    Any help is appreciated and I am happy to provide more information.
  • nomoresonys
    Badcaps Legend
    • Jan 2013
    • 12137
    • U.S.

    #2
    Re: Sony bravia kdl 46nx700 dim screen issue

    Can you post some good clear straight on detailed pictures of each board and one of the whole back to see how they are all connected?

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Sony bravia kdl 46nx700 dim screen issue

      Does it have Backlights level control? Backlights level control is not the same as Brightness (for Video).
      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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