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820-3330 chime, no image

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  • 820-3330 chime, no image

    I have 820-3330 water damage in lcd connector area. Connector replaced and jumper for backlight was put in place. Board turns on, chime and everything but no image or backlight. I replaced connector second time to make sure that I got it right.

    Gpu has power,
    =PP3V3_S5_LCD - present
    LVDS_DDC_CLK - present
    LVDS_DDC_DATA - present

    PP3V3_SW_LCD - 0 but it should be 3.

    It looks like board doesnt detect LCD, so I ordered new lcd and flex. Tested and get the same result, no image or backlight.
    Is there way to check if lcd being recognized? perhaps I got defective screen/flex?

    Or what other signals do I need to check for image? all lines on the connector are present, no short

  • #2
    External video present? GPU getting power at L8930?


    • #3
      Originally posted by dukefawks View Post
      External video present? GPU getting power at L8930?
      Yes I have power for at L8930 - 0.9v i assume it is close enough to 1v
      I don't get any external video (thunder to hdmi adapter)
      Last edited by Dmitry; 11-30-2016, 07:17 PM.


      • #4
        SMC_LID high?


        • #5
          I suspect u9000 shorted after lvds damaged.
          Did you check U9000? Voltage at Pin 1,3,5? Pin 5 to ground is shorted? Check at first 10s. Later enable signal will disappear probably.


          • #6
            No if U9000 is dead then the backlight will still work.


            • #7
              Originally posted by dukefawks View Post
              SMC_LID high?
              Duke thanks for suggestion, but I have checked LID before, it is high, 3v3

              U9000 doesnt have short, however one thing is strange. Pin 3 has low resistance to ground 0.565k, 0.122 diod mode. I still get 3v3 volts there, while screen pluged in.

              I dont have other 820-3330 motheboard but I compare to other two 15" boards and readings are complitly different, normal ~0.500 in diod mode. THis readings are with or without U9000, so it comes from power rail, any suggestions if thats the clue or it is normal?
              Is possible that 3v3 is present but current is low so it doesn't power the chip?
              I have replaced U9000 just in case.
              Last edited by Dmitry; 12-01-2016, 09:10 AM.


              • #8
                Connect a HDD with a good OSX that fully boots. Then connect an external screen. The GPU driver needs to be loaded for HDMI to work.


                • #9
                  Well since you asked to come back and check for external signal, I decided to make sure that my adapter works with working machine, and it doesn't. I reordered on, should arrive on monday.

                  Is there something I can do without adapter? what is the conclusion if I get external image? defective lcd, or flex?


                  • #10
                    Wait for a working adapter. IF there is external image we at least know the GPU is working.


                    • #11
                      I got adapter, there is no external image.

                      I put in bootable harddrive, macbook chimes, I waited for awhile, no image. So you think it is gpu?

                      I am not confident with this conclusion, because some laptop require LCD detect for external monitor to work. (non apple)
                      Last edited by Dmitry; 12-05-2016, 03:55 PM.


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