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Troubleshooting a Asus X541UVK

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    Troubleshooting a Asus X541UVK

    Hello everyone. Hope you're all doing great in this crazy world

    I am an IT person, but not much of an electronics guy (actually not at all), so I need your help with finding the cause that's stopping this laptop from powering on.

    Luckily I've found the boardview of this particular board on this forum, so this should make things a little bit easier for me (and hopefully for you deciding to give me a hand). I'm also attaching it here in case someone else is troubleshooting the same board in the future.

    First things first, I confirm that:

    1. Power adapter is OK
    2. DC IN is OK
    3. First 4 fuses are OK
    4. Mosfet is OK

    By OK, I mean 19V is present

    But then, there is a resistor (PR8938) which seems to be connected all over the board. At this stage I am not sure how I should resume troubleshooting. I tried to trace all linked components to this resistor, and 19V seems to be present everywhere.

    Don't want to misguide you, but visual inspection shows just a little bit of corrosion on capacitor C5564. There is no voltage going through, not the USB chip it's linked to (U5505).

    Thanks
    Attached Files
    Last edited by DanFen; 10-20-2020, 11:59 AM.

    #2
    Re: Troubleshooting a Asus X541UVK

    what is the voltage on PQ8902 pin 4 & 3 after check PR8938 voltage ? PU8701 all pins

    Comment


      #3
      Re: Troubleshooting a Asus X541UVK

      Hey

      PQ8902 pin4 = 24V
      PQ8902 pin3 = 19V

      PR8938 = 19V

      PU8701 pin1 = 0V
      PU8701 pin2 = 0V
      PU8701 pin3 = 3V
      PU8701 pin4 = 0V
      PU8701 pin5 = 0V
      PU8701 pin6 = 3V
      PU8701 pin7 = 0V
      PU8701 pin8 = 0.8V
      PU8701 pin9 = 5V
      PU8701 pin10 = 0.8V
      PU8701 pin11 = 0V
      PU8701 pin12 = 19V
      PU8701 pin13 = 5V
      PU8701 pin14 = 0V
      PU8701 pin15 = 0V
      PU8701 pin16 = 0V
      PU8701 pin17 = 5V
      PU8701 pin18 = 0V
      PU8701 pin19 = 0V
      PU8701 pin20 = 0V

      This controller is extremely small, it's very difficult to check (I hope the measured voltages are correct).

      Originally posted by techtiger View Post
      what is the voltage on PQ8902 pin 4 & 3 after check PR8938 voltage ? PU8701 all pins
      Last edited by DanFen; 10-21-2020, 07:42 AM.

      Comment


        #4
        Re: Troubleshooting a Asus X541UVK

        check voltage for 3.3 , 5 volt, powerbutton and so on.
        Attached Files

        Comment


          #5
          Re: Troubleshooting a Asus X541UVK

          the +3/+5V regulator is not working pin 8 voltage is low what is the voltage on
          PL8701 PL8702 voltage ? you have to check the resistance to GND on the 2 coils , what is the voltage SIO pin 85 ?
          Last edited by Techtiger; 10-21-2020, 10:31 AM.

          Comment


            #6
            Re: Troubleshooting a Asus X541UVK

            0V on the coils

            and SIO pin 85 is 0.8V too.

            Originally posted by techtiger View Post
            the +3/+5V regulator is not working pin 8 voltage is low what is the voltage on
            PL8701 PL8702 voltage ? you have to check the resistance to GND on the 2 coils , what is the voltage SIO pin 85 ?
            Last edited by DanFen; 10-21-2020, 11:09 AM.

            Comment


              #7
              Re: Troubleshooting a Asus X541UVK

              Never did it before, so could do with some hints.

              Power button is part of the keyboard.

              Originally posted by dellxps15 View Post
              check voltage for 3.3 , 5 volt, powerbutton and so on.

              Comment


                #8
                Re: Troubleshooting a Asus X541UVK

                Originally posted by DanFen View Post
                0V on the coils

                and SIO pin 85 is 0.8V too.
                check the resistance to GND on the all Gray coils first after check the voltage on R3061 R3015 both side's SIO pin 26 74 14 108 voltage ? voltage on JRST2402 ?
                Last edited by Techtiger; 10-22-2020, 02:08 PM.

                Comment


                  #9
                  Re: Troubleshooting a Asus X541UVK

                  Originally posted by DanFen View Post
                  Never did it before, so could do with some hints.

                  Power button is part of the keyboard.
                  on the attached guide pm_pwrbtn pin for volts here. measure and report back

                  +5vao +3vad +3vaddsw_on check both voltage and resistante to gnd (resistance without power )

                  Comment


                    #10
                    Re: Troubleshooting a Asus X541UVK

                    Hey, thanks for the help.

                    Resistance to ground on coils:

                    PL8701: 0.5 ohms
                    PL8702: 1.5 ohms

                    R3061: 0V on GND and 3.2V
                    R3015: 3.2V (both ends)

                    SIO pin 26: 3.3V
                    SIO pin 74: 3.3V
                    SIO pin 14: 3.3V
                    SIO pin 108: 0V

                    JRST2402: 3V (but there's nothing here, is it on purpose?)

                    EDIT: C3003 seems to be hotter than other components, and voltage seems to play between 0V and 1.1V rapidly.
                    EDIT 2: PU8701 is extremely hot (can't touch more than a second as it burns, I've actually burnt my finger)

                    Originally posted by techtiger View Post
                    check the resistance to GND on the all Gray coils first after check the voltage on R3061 R3015 both side's SIO pin 26 74 14 108 voltage ? voltage on JRST2402 ?
                    Last edited by DanFen; 10-22-2020, 02:38 PM.

                    Comment


                      #11
                      Re: Troubleshooting a Asus X541UVK

                      Short video attached.
                      Attached Files

                      Comment


                        #12
                        Re: Troubleshooting a Asus X541UVK

                        resistance on pin 8 of bios ?

                        Comment


                          #13
                          Re: Troubleshooting a Asus X541UVK

                          0.3 ohm

                          Originally posted by dellxps15 View Post
                          resistance on pin 8 of bios ?

                          Comment


                            #14
                            Re: Troubleshooting a Asus X541UVK

                            Originally posted by DanFen View Post
                            Hey, thanks for the help.

                            Resistance to ground on coils:

                            PL8701: 0.5 ohms
                            PL8702: 1.5 ohms

                            R3061: 0V on GND and 3.2V
                            R3015: 3.2V (both ends)

                            SIO pin 26: 3.3V
                            SIO pin 74: 3.3V
                            SIO pin 14: 3.3V
                            SIO pin 108: 0V

                            JRST2402: 3V (but there's nothing here, is it on purpose?)

                            EDIT: C3003 seems to be hotter than other components, and voltage seems to play between 0V and 1.1V rapidly.
                            EDIT 2: PU8701 is extremely hot (can't touch more than a second as it burns, I've actually burnt my finger)
                            PU8701/2 low resistance there is a short on this part , remove one PAD of each Coils PU8701/2 & test again what side is short in Diode mode , remove C3003 & test out of the bed if it's short

                            Comment


                              #15
                              Re: Troubleshooting a Asus X541UVK

                              remove the red marked jumper (clean with solder wick) and see if ic still get hot, if 3.3 and 5 volts comes on, see if resistance on coils has changed.
                              Attached Files

                              Comment


                                #16
                                Re: Troubleshooting a Asus X541UVK

                                Yep, still frying eggs.

                                Originally posted by dellxps15 View Post
                                remove the red marked jumper (clean with solder wick) and see if ic still get hot, if 3.3 and 5 volts comes on, see if resistance on coils has changed.

                                Comment


                                  #17
                                  Re: Troubleshooting a Asus X541UVK

                                  Removed just one side of these coils, Pin2 of PL8701, and Pin1 of PL8702.

                                  So in diode (beep) mode:

                                  PL8701 pin1: beep
                                  PL8701 pin2: no beep
                                  PL8702 pin1: no beep
                                  PL8702 pin2: beep

                                  C3003 removed (coils still one pad off), in beep mode: beep on GND and no beep on +3V.

                                  I hope this is what you've asked for

                                  Originally posted by techtiger View Post
                                  PU8701/2 low resistance there is a short on this part , remove one PAD of each Coils PU8701/2 & test again what side is short in Diode mode , remove C3003 & test out of the bed if it's short
                                  Last edited by DanFen; 10-24-2020, 03:38 AM.

                                  Comment


                                    #18
                                    Re: Troubleshooting a Asus X541UVK

                                    replace PU8701

                                    Comment


                                      #19
                                      Re: Troubleshooting a Asus X541UVK

                                      Will try to find a coil from a donor board. The problem is finding one that is exactly the same

                                      If I may ask, what makes you think PU8701 is the culprit and not PU8702 when the beeps result the same?

                                      Originally posted by techtiger View Post
                                      replace PU8701

                                      Comment


                                        #20
                                        Re: Troubleshooting a Asus X541UVK

                                        This is what I have has this code on them, but I don't know how to read them:

                                        3R3 716 P1H
                                        3.3UH/6.5A 20% CYNTEC/PEUB063T-3R3MS

                                        What I've found from other boards I have laying around:

                                        2R2 1114
                                        4R7 1117
                                        3R3 310 E43
                                        R82 311 30H
                                        R24 308 VLT
                                        R36 309 RFD
                                        1R0 306 8XA
                                        4R7 310 C8M
                                        4R7 030 ZC7

                                        Comment

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