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lenovo y50-70 VIN mosfets gets hot & possible short

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    lenovo y50-70 VIN mosfets gets hot & possible short

    looking help on lenovo y50-70 mboard: la-b111p zivy2

    laptop had shorted capacitor on B+ battery rail and was dead, CHG_B+ PC305

    i replaced cap with same healthy cap and laptop started working, i noticed
    input mosfest got hot when i start laptop, but when battery is connected vin mosfets get insanely hot but laptop charges and works with battery

    -i can hear small spark sound when charger is connected
    something draws lots of current but i cant figure out what component it is
    -BATT+ mosfet PQ303 gets also pretty hot but when i charge battery it gets insanely hot and it is next to cap i changed
    -PU301 battery charge ic is not getting hot
    -also pch gets warm / sometimes hot
    -PL302 CHG measuring 88 kohm to ground

    #2
    Re: lenovo y50-70 VIN mosfets gets hot & possible short

    Laptop should not be used as a micro furnace.

    Remove all power.

    Meter in resistance mode.

    Check the resistance for each mosfet as follows:

    Source and drain
    Source and gate
    Gate and drain

    Post the values.

    Checking for low resistance = shorted mosfet.

    Comment


      #3
      Re: lenovo y50-70 VIN mosfets gets hot & possible short

      replace mosfet. its burned and have higher resistance. your vin voltage should be lower because of it

      Comment


        #4
        Re: lenovo y50-70 VIN mosfets gets hot & possible short

        Originally posted by ktmmotocross View Post
        replace mosfet. its burned and have higher resistance. your vin voltage should be lower because of it
        Maybe but may not be also. Lets wait for the measurements. Heating up could be for other reasons as well.

        Comment


          #5
          Re: lenovo y50-70 VIN mosfets gets hot & possible short

          mosfets get insanely hot even laptop is off and i charge battery only


          battery charge mosfets

          PQ303

          BATT+, B+ = 3.5Ω (short?)
          BATT+, DISCHG_G = 187Ω
          B+, DISCHG_G = 187Ω

          PQ310

          CHG_B+, gate =1200Ω
          CHG_B+, LX_CHG =53.5Ω
          gate, LX_CHG =1185Ω

          PQ312

          LX_CHG, DL_CHG = 1584Ω
          LX_CHG, GND = 226Ω
          GND, DL_CHG =431Ω


          PQ501

          1.35V_B+, SW_1.35V = 1.73kΩ
          1.35V_B+, DH_1.35V = 1.75kΩ
          DH_1.35V, SW_1.35V = 5.3Ω (short?)

          PQ502

          SW_1.35V, GND = 247Ω
          SW_1.35V, DL_1.35V = 890Ω
          DL_1.35V, GND = 110Ω

          input vin mosfets

          PQ301

          VIN, P2 = 70kΩ
          VIN, P2-1 = 71kΩ
          P2-1, P2 = 150Ω

          PQ302

          P3, P2 = 1.8Ω (short?)
          P3, P2-1 = 152Ω
          P2-1, P2 = 152Ω
          Last edited by swammyw; 12-02-2021, 06:27 PM.

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            #6
            Re: lenovo y50-70 VIN mosfets gets hot & possible short

            Take PQ301/302/303 out of circuit and measure resistance between

            Pin1 to pin4
            Pin4 to pin5
            pin1 to pin5

            Repeat the same on pcb after removing the mosfets and draw your own conclusion.

            Comment


              #7
              Re: lenovo y50-70 VIN mosfets gets hot & possible short

              can i change ao4455 to ao4433, some values are diffrent a little
              Attached Files

              Comment


                #8
                Re: lenovo y50-70 VIN mosfets gets hot & possible short

                No, there is huge difference in pulsed drain current. 4433 Will instantly burn out.

                Comment


                  #9
                  Re: lenovo y50-70 VIN mosfets gets hot & possible short

                  ok thanks

                  Comment

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