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  1. #1
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    00163 No Backlight

    This was sent in with liquid damage. I have 5v on the LCD detection filter, 5v in to the backlight driver, BKLT enable present, continuity along all these backlight traces, the voltage divider for the first transistor isn't being shorted by the driver. If I manually short it, I get 12V on the backlight because driver is still not telling the second transistor to switch power on the coil. I am stumped. LCD is definitely the right year, done NVRAM reset everytime and I see flashing folder with a flashlight. Replaced driver multiple times including at the same time as the mosfets. Using new drivers everytime from the same batch so I tried a donor board no change. I2C lines to the connector are good now, had to replace the connector but diode mode looks good now. TIA!

  2. #2
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    Re: 00163 No Backlight

    Cehck the feedback line continuity from LCD to the BL controller.

  3. #3
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    Re: 00163 No Backlight

    It's like the last line in my post "I2C lines to connector are good now" Double checked continuity just now for peace of mind. Both data lines (I2C_BKLT_SCL and SDA) are electrically continuous between the LCD conn and backlight driver. Here are my diode mode readings for the other pins of J8300 since I did replace the connector so its possible I missed something there.
    1 - 1.205
    2 - OL
    3 - 0.544
    4 - 0.544
    5 - 0.659
    6 - 1.717
    7 - 1.721
    8 - 0.641
    9 - 0.620
    10 - 0.645
    11 - OL
    12 - OL
    13 - 0.002
    14 - OL
    15 - OL
    16 - 0.002
    17 - OL
    18 - OL
    19 - 0.002
    20 - OL
    21 - OL
    22 - 0.002
    23 - OL
    24 - OL
    25 - 0.002
    26 - 0.002
    27 - 0.002
    28 - 0.570
    29 - 0.570
    30 - 0.570

  4. #4
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    Re: 00163 No Backlight

    Stepping back a bit, what voltages are you getting from F7700, thru R7700, Q7706, L7710 and D7701?

  5. #5
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    Re: 00163 No Backlight

    12.6V through R7700. Q7706 has 12.6 sitting on its input, 0 output so 0 all the way down to the connector.

 

 

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