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820-2915 not turning on

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  • 820-2915 not turning on

    Have a 820-2915 with soda damage. Replaced everything affected by the spill but still no fan spin.

    Checked power rails and pp5v_sus is pulsing up to 0.135V then 0v. Replaced Q7840 and D2400 but same results. Checked and have no shorts. Drawing steady 0.15amps on power supply

    What to try next?

  • #2
    Just warning even if if you fix this it will have a dead GPU

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    • #3
      Resistance to ground at PP5V_S5 rail?
      Disconnect R5805 and see if symptom changes.

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      • #4
        I plan on replacing the GPU with a new one.

        0.434

        0.403 with R5805 removed

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        • #5
          5V with it removed

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          • #6
            Bad U5805 I suppose.
            Do you get short to ground at R5806?
            Does the board start now?

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            • #7
              No short on R5806

              Put R5805 back on and replaced U5805 but still not starting

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              • #8
                fan spin after trying apple charger instead of power supply

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                • #9
                  Does it work now?
                  It requires to connect bench power supply through 85W cable, when no charger available...

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                  • #10
                    Yes but pink lines through screen... should be fixed after GPU replacement.

                    cable on bench power supply is suppose to be 85 watt but board only draws 0.15 amps on it. Power up no problem on standard apple 85 watt ac adapter

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