ThinkPad E14 Gen 4 AMD NM-E501 dead

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  • rumpumpel1
    Senior Member
    • Jul 2019
    • 154
    • germany

    #1

    ThinkPad E14 Gen 4 AMD NM-E501 dead

    I have an E14 Gen 4 AMD that shows no signs of life.
    When connected to the charger the board initially drew 30 mA at 10 V.
    The thermocamera showed a hot spot at one edge of the PD controller. I therefore replaced the PD controller, after which the board drew 5 mA at 20 V.
    Further investigation revealed that the power switch UT5 (NX20P5090UK) was not activated. The EN# signal is missing. This is supposed to be generated by the PD controller.

    From then on I started using the battery instead of the charger.
    With the battery the main power rail V9B+ is present (11.4 V) but all the other power rails are off.

    I then looked at 3VALW and 5VALW. Both require the enable signal EC_USM which is supposed to be provided by the EC.
    However, the EC is powered by 3,3 V but does not provide this signal.
    Next I measured various resistances against GND:
    PL4903 3VALW 400 Ohm
    PL4904 5VALW 400 Ohm
    LDO3 4 kOhm
    LDO5 40 kOhm
    These values are comparable to those of an E14 Gen 3 AMD mainboard which I am using as point of reference.

    I then took the same measurements for all other power rails. I also opened various jumpers to rule out some defect behind the jumper.
    All the measurements turned out to be reasonable.

    What else could I do to trace down the fault?

    schematics can be found here: https://www.badcaps.net/forum/troubl...e501-schematic

  • mon2
    Badcaps Legend
    • Dec 2019
    • 14247
    • Canada

    #2
    UT5 (NX20P5090UK) was not activated. .The EN# signal is missing.
    There is another case of the same issue from last week here on this forum.

    What is the exact voltage to ground of the EN# signal?

    Comment

    • rumpumpel1
      Senior Member
      • Jul 2019
      • 154
      • germany

      #3
      The EN# signal has 3,2V to GND.

      Comment

      • mon2
        Badcaps Legend
        • Dec 2019
        • 14247
        • Canada

        #4
        So the load switch is DISABLED. This line needs to be LOW = 0v to enable the load switch.

        In the other case, this load switch was defective. The ENABLE was active yet the voltage did not pass through.

        Measure the voltage to ground of the output of this load switch. What is the resistance to ground?

        Click image for larger version

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        Last edited by mon2; 08-10-2025, 05:49 AM.

        Comment

        • mon2
          Badcaps Legend
          • Dec 2019
          • 14247
          • Canada

          #5
          Confirm the power rails on UT2. This chip is driving this EN# signal. Be sure the soldering of this replacement part is ok. Flux and reflow if necessary.

          Comment

          • rumpumpel1
            Senior Member
            • Jul 2019
            • 154
            • germany

            #6
            The output of the load switch is 0V.
            Resistance to GND is 550 Ohm (my reference board also shows 550 Ohm).

            UT2 gets 20V at Pin 31 (VBUS_IN).
            I checked the soldering from all four sides using a microscope. It looked ok.
            Last edited by rumpumpel1; 08-10-2025, 06:26 AM.

            Comment

            • mon2
              Badcaps Legend
              • Dec 2019
              • 14247
              • Canada

              #7
              Confirm the voltage to ground for:

              RPT3 (pull-up resistor network that parks the SNK_PS_EN line to a high state) - test both sides of this resistor network to confirm the presence of +LDO_3V3

              UT2 pin 33 (3V3_OUT)
              UT2 pin 32 (5V_IN)
              UT2 pin 11 (VCONN_IN)

              Comment

              • rumpumpel1
                Senior Member
                • Jul 2019
                • 154
                • germany

                #8
                RPT3 has 3,2V on one side and 3,0 V on the other side.
                UT2 pin 33 = 3,2V
                UT2 pin 32 = 0 V
                UT2 pin 11 = 0 V

                Comment

                • mon2
                  Badcaps Legend
                  • Dec 2019
                  • 14247
                  • Canada

                  #9
                  +5VALW appears to be missing. Remove all power and measure the resistance to ground of +5VALW.

                  Comment

                  • rumpumpel1
                    Senior Member
                    • Jul 2019
                    • 154
                    • germany

                    #10
                    as described above: the resistance of 5VALW to GND is 400 Ohm.

                    Comment

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