Please help friends, thinkpad t480 nm-b501 is dead

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  • fredyjbi
    Senior Member
    • Feb 2021
    • 144
    • malaysia

    #1

    Please help friends, thinkpad t480 nm-b501 is dead

    Please help friends, thinkpad t480 nm-b501 is dead, help me fix it, thank you
    usb meter 20v 0.00 amp, after I took the VSYS measurement the drop was only `9.2v which should have been 10.2v I measured from a normal matherboard machine, the VSYS path resistance to ground diode mode is 1900 thank you

    LINK to Schematic -> https://www.badcaps.net/forum/troubl...b501-schematic
    Last edited by SMDFlea; 04-16-2024, 03:47 PM. Reason: Posted link to schematic
  • mon2
    Badcaps Legend
    • Dec 2019
    • 13866
    • Canada

    #2
    Remove all power. Meter in resistance mode (not diode mode). One meter probe on VSYS; other meter probe to ground. What is the measurement? Also share the scale used on your meter. Units should be in ohms; kohms (kilo-ohms); mega-ohms, etc.

    With truly a 0A current draw, this means that the power adapter is sending out the negotiated power but the logic board is not consuming it. Confirm the condition of the fuses that are in series with this power path. Check for a voltage to ground on each side of each fuse.

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    • fredyjbi
      Senior Member
      • Feb 2021
      • 144
      • malaysia

      #3
      Originally posted by mon2
      Remove all power. Meter in resistance mode (not diode mode). One meter probe on VSYS; other meter probe to ground. What is the measurement? Also share the scale used on your meter. Units should be in ohms; kohms (kilo-ohms); mega-ohms, etc.

      With truly a 0A current draw, this means that the power adapter is sending out the negotiated power but the logic board is not consuming it. Confirm the condition of the fuses that are in series with this power path. Check for a voltage to ground on each side of each fuse.
      thank you in advance sir or if you are interested in helping me, I set the avometer to auto resistor mode, VSYS shows OL

      Comment

      • mon2
        Badcaps Legend
        • Dec 2019
        • 13866
        • Canada

        #4
        With an OL resistance to ground, there is no short here. Configure your meter to DC volts mode with a scale of 30 volts or higher. Measure the voltage to ground on PQ101 which is the 2 * DCin mosfet in a single package. There is another pair @ PQ102.

        Pin # 2 should have the 20v from the power adapter. Confirm this voltage. Also the voltage to ground of pin # 7.

        Comment

        • fredyjbi
          Senior Member
          • Feb 2021
          • 144
          • malaysia

          #5
          Originally posted by mon2
          With an OL resistance to ground, there is no short here. Configure your meter to DC volts mode with a scale of 30 volts or higher. Measure the voltage to ground on PQ101 which is the 2 * DCin mosfet in a single package. There is another pair @ PQ102.

          Pin # 2 should have the 20v from the power adapter. Confirm this voltage. Also the voltage to ground of pin # 7.
          Thank you for your interest in helping me, sir
          and sorry sir I'm late in giving an answer, the bad news turns out the PL202 is short to ground VCC3M, 2v injection on the PL202 SOC is hot bad SOC, thank you​

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