macbook pro 820-2914-A - no image / no backlight

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  • cruiser_
    Senior Member
    • Nov 2019
    • 124
    • Ireland
    #1

    macbook pro 820-2914-A - no image / no backlight

    hi,
    i am working on this macbook pro that had amd gpu shorted.
    it now chimes and boots but there is no backlight.
    Can't see an image with a flashlight either...

    I tracked it down to:
    - No LCD_PWR_EN - u9600 enables
    - No LCD_BKLT_EN - u9600 enables
    - No EG_BKLT_EN from
    - No EG_LCD_PWR_EN

    I forced EG* signals to 3.3V but am still not getting signals from U9600.
    U9600 has all three power inputs (PP3V3_S0, PP1V8_S0, PP1V2_S0).

    LCD_PWR_EN is not pulled down by Q9607 (GMUX_S3_PD_GND above 2V).

    what does the gmux chip need to output LCD_*EN signals?
    what else to check before I go forcing these?
    Last edited by cruiser_; 12-27-2022, 01:39 PM.
    Tags: None
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