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HP laptop with no power. Can you help me understand the DA0R75MB6C1 schematics?

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    #41
    Re: HP laptop with no power. Can you help me understand the shematics?

    Originally posted by mattpd View Post
    ISL6277A removed

    Pin 18 to ground = 2.5ohm
    Pin 19 to ground = 2.5ohm
    Pin 26 to ground = 15ohm
    Pin 32 to ground = 0.5ohm
    Pin 35 to ground = 1.5ohm
    Pin 45 to ground = 11ohm

    Removing FETs next to test them...

    FETs removed:

    On PQ3, PQ4, and PQ6 resistance between S and D is open, until touching the gate with red probe and then 0.5ohm between S and D (seems normal to me).

    PQ7 the resistance between S and D is 160ohm until touching gate and then 0.5ohm.

    So it seems like as though PQ7 is working (opening and closing) but it has a much lower resistance between S and D than PQ6 (which is the same part number). PQ7 must be bad, right?
    Make sure you discharge the gate when testing if it's OFF. You can do so by shorting gate to source or inverting the probes of the meter (positive on source, negative on gate. When you short gate and source it should definitely be open. And you can do the diode test also as suggested before. From source to drain will show you the bodydiode.

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      #42
      Re: HP laptop with no power. Can you help me understand the shematics?

      Originally posted by paulstef View Post
      Make sure you discharge the gate when testing if it's OFF. You can do so by shorting gate to source or inverting the probes of the meter (positive on source, negative on gate. When you short gate and source it should definitely be open. And you can do the diode test also as suggested before. From source to drain will show you the bodydiode.
      Upon checking them again, it seems like they all work. PQ7 is behaving exactly like PQ6 as they should because they are the same part.

      How about the output pins of the ISL chip? I see that Phase 1 and Phase 2 are both short, which I guess I need to investigate. But what about the other shorts like VSENS, VSENS_NB, RTN, and VIN. Is there any reason they would be such low resistance, or is there a problem there too?

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        #43
        Re: HP laptop with no power. Can you help me understand the shematics?

        how to testi the FETs using the diode function on your multimeter?

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          #44
          Re: HP laptop with no power. Can you help me understand the shematics?

          Originally posted by karim_hassan777 View Post
          how to testi the FETs using the diode function on your multimeter?
          Works for most FETs : https://www.youtube.com/watch?v=RBJGOOTEwfU

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