A2338 820-02020 No backlight

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  • loic2907
    Member
    • Feb 2020
    • 31
    • France
    #1

    A2338 820-02020 No backlight

    Hi all,
    I face a problem with this motherboard.
    Working perfectly in HDMI.

    First problem liquid damage.
    Problems were on RD560 and RP800, these 12V with sense was dead.
    And pin 9 on UC710 too.

    RD560, RP800, UC710, UD560, UP800 has been replaced.

    Now, on the screen (JP600) I have :

    PP3V3_SW_LCD_CONN : 3V
    EDP_PANEL_1V8_EN : 1.8V
    PP5V_SW_LCD_CONN : 5V
    PP5V_CAM : 5V
    LPDP_INT_HPD : 0V
    PPVOUT_LCDBKLT : 0V
    I2C_BKLT_SDA : Have DATA with oscilloscope
    I2C_BKLT_SCL : Have CLOCK with oscilloscope

    On the UP800, pin 17 : BKLT_EN_R, I have 0V too.
    I did a bridge on this pin, and I had PPVOUT_LCDBKLT : 50V.
    No backlight visible on the screen with PPVOUT_LCDBKLT at 50V.

    I tried my screen on another A2338, this screen seems to have lines but works perfectly.

    Now, I'm short of ideas.
    If some of you have a new one to help
    Attached Files
    Last edited by loic2907; 03-07-2023, 03:10 AM.
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 14074
      • Canada
      #2
      Re: A2338 820-02020 No backlight

      Backlight is a function of the LCD being detected and the lid sensor able to sense that the display is open.

      Check the logic level of the lid status. This is from a hall effect sensor in the trackpad.

        Comment

        • mon2
          Badcaps Legend
          • Dec 2019
          • 14074
          • Canada
          #3
          Re: A2338 820-02020 No backlight

          Also 50v is too high for the backlight voltage. Be sure the backlight led strips are connected at the lcd display connector.

            Comment

            • loic2907
              Member
              • Feb 2020
              • 31
              • France
              #4
              Re: A2338 820-02020 No backlight

              Originally posted by mon2
              Backlight is a function of the LCD being detected and the lid sensor able to sense that the display is open.

              Check the logic level of the lid status. This is from a hall effect sensor in the trackpad.
              Hi thanks for you reply.
              IPD_LID_OPEN_1V8 is 1.8V
              Screen connected and close, in HDMI I have the log on the session if I open the screen, it desapear and print the background wallpaper only.
              LID is working great so ?
              For the 50V, the 2 connector on the board of the screen are connected too.

                Comment

                • 5132857
                  New Member
                  • Jun 2023
                  • 1
                  • canada
                  #5
                  Re: A2338 820-02020 No backlight

                  Hi, I need the part number of the rd560 and where can I buy it? Thanks!

                    Comment

                    • jansmola89
                      #5.1
                      jansmola89 commented
                      12-04-2023, 09:41 AM
                      Editing a comment
                      Hi. Did you found it somewhere? Is it possible to get RD560 from another one mainboard?I'd checked A1706, A1707, A1708, A1502 mainboards but no luck there
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