HP 840 g1 Turning on DC and read 0.070 then goes off simultaneously.

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  • Oj computer
    Member
    • Dec 2021
    • 38
    • Nigeria
    #1

    HP 840 g1 Turning on DC and read 0.070 then goes off simultaneously.

    Pls i also have same issue on HP 840 g1
    Turning on DC and read 0.070 then goes off simultaneously.
    At first MOSFET I have 19v at gate comings from acdrive instead of 25v.
    When checked the the charging
    Acdet is 2.6 cmsrc is 19, but vcc is 0v instead of 19v.
    After that, I jumped 19v to vcc then acdive changed to 25v but still no changes to the pc.
    Am having 2.47 at on/off switch pin
    Kindly help.
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 13956
      • Canada
      #2
      Re: HP 840 g1 Turning on DC and read 0.070 then goes off simultaneously.

      1) do you have a battery installed when connecting the AC power adapter ?

      If yes, remove the battery and test again.

      For now, the battery is not required to test the logic board so the battery can be removed.

      2) It is a good sign that the gate voltage is ~25v which is required to turn ON the DC IN mosfets.

      3) Your DCIN mosfets need to be inspected as at least one is defective.

      4) I think the schematic may have errors - check the wiring of the GATE pin on the DCIN mosfets - to me, it does not look correct on how the schematic is showing the GATE trace for Q6012.

      Can you confirm where pin # 4 of Q6012 is truly connected ?
      Attached Files

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        • mcplslg123
          Badcaps Legend
          • Jun 2015
          • 7262
          • india
          #3
          Re: HP 840 g1 Turning on DC and read 0.070 then goes off simultaneously.

          Dont jumper 19v to VCC pin. Replace the 10 ohms resistor instead if its bad. Do check caps connected to this resistor as well. Sometimes the caps become half shorted when vcc resistor is burnt.

            Comment

            • Udemzy
              Senior Member
              • May 2017
              • 151
              • Guatemala
              #4
              Re: HP 840 g1 Turning on DC and read 0.070 then goes off simultaneously.

              With a reading of 0.070, check if rsmrst# is available and if the SLP signals are coming after power button is trigger.
              2.47v is enough to trigger it.

                Comment

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