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Alienware M17 R3 - LA-J521P - CPU Fan not working.

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    Alienware M17 R3 - LA-J521P - CPU Fan not working.

    Hi.
    I got this laptop with an overheating issue.
    After opening, I found both fans clogged with dust and nicotine.
    GPU Fan started to work after the disgusting cleaning, but the CPU Fan is dead. I ordered a new fan and replaced it, and it's still not working.
    Further diagnostics show that the PWM signal from the EC Chip is OL.
    Fan connector:
    1 = +12V_FAN
    2 = Open Line 0V This line comes from the EC chip. CPU_FAN_PWM
    3 = +5VS - CPU_FAN_FB
    4 = GND

    I think because the fan was stuck for so long it damaged the line from the EC. The line jas continuity to the resistor next to EC, but the measurement is OL.
    I reflowed the EC, and still the same. That specific line is dead inside the EC.
    I disconnected the Pin 2 from the MOBO and jumped a wire from the GPU fan, and it worked, but both fans stayed on full speed.
    The GPU fan was on full speed before, as a result of the EC not recognising the CPU fan
    The question is, is there any other way to make the CPU fan work other than to jump the PWM signal from the GPU fan?
    Thanks.

    Link to Schematic & Boardview - https://www.badcaps.net/forum/docume...atic-boardview
    Attached Files
    Last edited by SMDFlea; 03-27-2025, 06:25 AM. Reason: Link to Schematic & Boardview
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