Lenovo G50-80 20V ISSUE

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  • motanya
    Senior Member
    • Nov 2021
    • 160
    • Kenya
    #1

    Lenovo G50-80 20V ISSUE

    I have a Lenovo G50-80 motherboard. aclu3/aclu4 UMA NM-A362 REV1.0. That if I connect the charger main power rail voltage moves up and down a maximum of 4v and zero continuously, I opened jumper PJ708 laptop powered on but no vcore of course. If I close the jumper and remove coil pl9 the initial problem remains. Now I have figured out the issue is the PC988 capacitor because if removed the laptop powers on well and displays if I replace the same capacitor from a working board the main problem remains. What might be the problem?
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    • mon2
      Badcaps Legend
      • Dec 2019
      • 14022
      • Canada
      #2
      Re: Lenovo G50-80 20V ISSUE

      Remove all power. Check the resistance to ground of the main power rail that is fluctuating.

      What is the resistance?

        Comment

        • motanya
          Senior Member
          • Nov 2021
          • 160
          • Kenya
          #3
          Re: Lenovo G50-80 20V ISSUE

          Originally posted by mon2
          Remove all power. Check the resistance to ground of the main power rail that is fluctuating.

          What is the resistance?
          41.32kOhms

            Comment

            • mon2
              Badcaps Legend
              • Dec 2019
              • 14022
              • Canada
              #4
              Re: Lenovo G50-80 20V ISSUE

              This is a good and high resistance. No short on this rail.

              Is this resistance WITHOUT PC988 installed ?

              If yes, the fault is with this capacitor being shorted / partially shorted and causing the voltage rail to swing due to a higher than normal current draw.

              Respectively, measure the resistance across the PC988 component if it is off the logic board and on your work bench. It should continue to show a lower than normal resistance.

              It is a bulk capacitor and ideally should be replaced with this capacitance value or close to. Be cautious of the voltage rating of the cap since this is the high side power rail from your power adapter.

                Comment

                • ash91
                  Member
                  • Jun 2023
                  • 31
                  • SAUDI
                  #5
                  Re: Lenovo G50-80 20V ISSUE

                  try replace PQ40 and check the resistance after.

                    Comment

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