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Y50-70 turns on, no video, fans dont spin

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    Y50-70 turns on, no video, fans dont spin

    Hello,

    My Lenovo Y50-70 turns on but i have no video, fans dont spin, keyboard lights turns on, no ssd activity.

    I removed battery, hdd, rams, bios battery, then pressed power button for 30 sec to drain out all energy, still same thing, i did check both mosfets on power module of the board, pq301 and pq302, i get 20,5V on all pins except one pin that have 8.7V

    Connected external keyboard, tried on all 3 usb ports, no leds on the keyboard, neither numlock, checked voltage on usb pins, i only have 5.1V on 1 pin, rest 0V

    I have 1.4v on PL502 with power on, addpter is connected and working properly, got 20.5V on both channels.

    U11 have 3.3v on pin 5 when power is on

    U23 have 3.3v on both 8,9 pins

    Any ideas what to check more?

    Thank You

    Board model is ZIVY2 LA-B111P
    REV: 1A

    Schematics:

    #2
    Test the resistance to ground of each inductor. No power during these measurements. Checking for a lower than normal resistance.

    Comment


      #3
      mon2

      PL1201 - 115 KOHM
      PL702 - 3,6 OHM
      PL302 - 35 KOHM
      PL402 - 42 OHM
      PL404 - 79 KOHM
      PL502 - 168,6 OHM

      Comment


        #4
        all somebody

        Comment


          #5
          PL1201 - 115 KOHM
          PL702 - 3,6 OHM
          PL302 - 35 KOHM
          PL402 - 42 OHM
          PL404 - 79 KOHM
          PL502 - 168,6 OHM
          PL402 is too low. The rest look ok. The other low resistance rails are normal resistance measurements for low voltage rails.

          Double check this resistance again. If still under 100 ohms, there may be a fault here. Flux and lift up one leg of PL402. Take care to not lift the PCB pad for this part.

          The check this resistance again. Is the lower resistance on the producer side (PU401) or on the consumer side (+3VALWP) of this rail? Suspecting the consumer side.

          Click image for larger version

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