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Dell E7240 Adapter not recognized

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    Dell E7240 Adapter not recognized

    Hi, I got E7240 after water damage.
    After cleaning laptop starts normally but is not recognize adapter (genuine one) and not detecting battery also (LAptop can work on battery but will not charge it)
    It can work on adapter alone and with battery but is not recognized. I checked middle pin and 3.2V is present.
    I tracked NB_PSID up to U38 chip pin A55 and there is 3.2V, I removed U38 cleared all pads and still this same with no change.
    Please some1 help me where I can look for reason of this faults.

    Many thanks
    Last edited by Beertimenow; 03-12-2020, 08:38 AM.

    #2
    Re: Dell E7240 Adapter not recognized

    Check PU111 and measure continuity between pin 3 and 4, most often the problem is PU111. Dell uses one wire protocol to communicate with the charger (Dallas chip inside the charger), so you can check the signal with the oscilloscope only. Voltage measured means nothing. Just check the continuity between middle pin and pin A55, also check resistance - PS_ID to GND.
    P.S. You can remove PU111 and bridge pin 3 to pin 4, for testing purposes.
    Check PD1 and PD2 for the battery problem.
    Last edited by Vesko356; 03-12-2020, 10:20 AM.
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      #3
      Re: Dell E7240 Adapter not recognized

      Hi, thanks for reply, I already checked PU111 yesterday I took it out and bridge pins 3 and 4.
      From A55 to ground when laptop is off I got 07.5 M Ohms,but when is on i got short to ground.
      From A55 to middle pin no continuity when is off, got continuity when is on with 70 Ohms resistance.
      Unfortunately I dont have oscilloscope

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        #4
        Re: Dell E7240 Adapter not recognized

        Originally posted by Beertimenow View Post
        Hi, thanks for reply, I already checked PU111 yesterday I took it out and bridge pins 3 and 4.
        From A55 to ground when laptop is off I got 07.5 M Ohms,but when is on i got short to ground.
        From A55 to middle pin no continuity when is off, got continuity when is on with 70 Ohms resistance.
        Unfortunately I dont have oscilloscope
        Find what is the reason for short to GND, most probably PD5 is the problem, but check all components in the line before pin 3 of PU111 (check all resistors and PQ2, PQ3).
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        All donations to Badcaps are welcome.
        Become a Badcaps supporter
        >>>>> click on this link to donate <<<<<
        Thanks to all supporters.​
        ----------------------------------------------------------------------------------------------------------------------------------------------------------
        Doctrina est fructus dulcis, radicis amarae.
        .

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          #5
          Re: Dell E7240 Adapter not recognized

          Originally posted by Vesko356 View Post
          Find what is the reason for short to GND, most probably PD5 is the problem, but check all components in the line before pin 3 of PU111 (check all resistors and PQ2, PQ3).
          PD5 it looks like missing component, from schematic I see it should be switching diode there. and should go to +5_ALW (not sure what is alw stand for)

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            #6
            Re: Dell E7240 Adapter not recognized

            When is on it looks like short coming from A37 #PSID_DISABLE cannot find PR13 and PR11 to check them.
            Boardview will be amazing for this.

            When is LCD connected short is on: PQ2 - all pins, PQ3 - 2 pins , PL3 - both pins. I marked all points with short around PQ2 and 3



            That is more weird:
            If I run laptop without lcd connected it not short to ground anymore, but I cannot enter to bios when I connect monitor via HDMI and try to enter bios its showing this error:
            Attached Files
            Last edited by Beertimenow; 03-12-2020, 03:39 PM.

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              #7
              Re: Dell E7240 Adapter not recognized

              Pretty weird, remove the bridge between pin 3 and 4 of the PU111 and find out where is the short on pin 3 or on pin 4, looks like water damage motherboard layer problem.
              ----------------------------------------------------------------------------------------------------------------------------------------------------------
              All donations to Badcaps are welcome.
              Become a Badcaps supporter
              >>>>> click on this link to donate <<<<<
              Thanks to all supporters.​
              ----------------------------------------------------------------------------------------------------------------------------------------------------------
              Doctrina est fructus dulcis, radicis amarae.
              .

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                #8
                Re: Dell E7240 Adapter not recognized

                PD5 is no stuff.
                Short to ground must be measured with all power source disconnected. Measuring it with power makes no sense and risk damaging components.
                OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

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                  #9
                  Re: Dell E7240 Adapter not recognized

                  I give up with this, not everything can be fixed, maybe for someone will be ease fix, but I got enough.
                  Thanks guys for all the help

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