Toshiba L755-13N no power.

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  • rickybucalan
    Badcaps Veteran
    • May 2013
    • 322
    • philippines

    #1

    Toshiba L755-13N no power.

    hello everyone i need your help.

    i got this L755 i3 laptop with no power. can't find right schematic diagram (DA0BLGMB6D0).

    I found shorted fets nikos P1203ED replace with new one but it still get shorted too.

    pls. see attached picture of some test i made.
    Attached Files
  • ala_borbe
    aka Donald
    • Apr 2011
    • 1625
    • Malta

    #2
    Re: Toshiba L755-13N no power.

    try this
    Attached Files
    Im Back... sort of...

    Comment

    • meritosari
      Senior Member
      • Oct 2010
      • 774
      • Indonesia

      #3
      Re: Toshiba L755-13N no power.

      try this:
      Attached Files

      Comment

      • rickybucalan
        Badcaps Veteran
        • May 2013
        • 322
        • philippines

        #4
        Re: Toshiba L755-13N no power.

        hello guys i found shorted line that suppose to be not.

        on page 36. system 5v/3v PU5 pin 6VIN is shorted

        i already remove PU5 it still shorted

        i also remove some caps PC85, PC74 on the same line still got shorted. dont no were to find more.

        need help tnx...
        Attached Files

        Comment

        • meritosari
          Senior Member
          • Oct 2010
          • 774
          • Indonesia

          #5
          Re: Toshiba L755-13N no power.

          so 19v all short-circuit path. try searching in the scheme of the word "vin". from page 37 onwards. so many caps in the vin lines.

          I saw in the scheme have been marked with a line box D3B
          Last edited by meritosari; 02-26-2015, 12:51 PM. Reason: wrong

          Comment

          • rickybucalan
            Badcaps Veteran
            • May 2013
            • 322
            • philippines

            #6
            Re: Toshiba L755-13N no power.

            Originally posted by meritosari
            so 19v all short-circuit path. try searching in the scheme of the word "vin". from page 37 onwards. so many caps in the vin lines.

            I saw in the scheme have been marked with a line box D3B

            i still cant find the fault component. here i attached file on page 36,37,38,39 and 41. i mark red line that are shorted and even though i removed all caps in the line including ics U3, PU4 PU1,PU8,PU5 and mosfets that mark O.

            any idea. gu
            Attached Files

            Comment

            • meritosari
              Senior Member
              • Oct 2010
              • 774
              • Indonesia

              #7
              Re: Toshiba L755-13N no power.

              +vtt rails short?

              did you try isolate by remove PL4, so we focus on vin rails?
              maybe pq13,pq18, pq23 are short too

              Comment

              • rickybucalan
                Badcaps Veteran
                • May 2013
                • 322
                • philippines

                #8
                Re: Toshiba L755-13N no power.

                Originally posted by meritosari
                +vtt rails short?

                did you try isolate by remove PL4, so we focus on vin rails?
                maybe pq13,pq18, pq23 are short too
                +vtt is short

                yeah.i removed that also but the short is still on +vtt line

                PQ13, PQ18 PQ23 is not shorted.

                Comment

                • meritosari
                  Senior Member
                  • Oct 2010
                  • 774
                  • Indonesia

                  #9
                  Re: Toshiba L755-13N no power.

                  I still can not understand, if from page 36 to page 41 + vin has a short-circuit, should pq20 on pins 4 and pq15 on pin 3 is also a short-circuit

                  quickly find a short-circuit path usually use a PSU that has a current and voltage limits

                  to isolate pu8 of rail + vin try to lift pr42, because small parts I used to simply shift course and avoid the loss of these components. I often use two pieces of solder to slide
                  Attached Files

                  Comment

                  • rickybucalan
                    Badcaps Veteran
                    • May 2013
                    • 322
                    • philippines

                    #10
                    Re: Toshiba L755-13N no power.

                    Originally posted by meritosari
                    I still can not understand, if from page 36 to page 41 + vin has a short-circuit, should pq20 on pins 4 and pq15 on pin 3 is also a short-circuit

                    quickly find a short-circuit path usually use a PSU that has a current and voltage limits

                    to isolate pu8 of rail + vin try to lift pr42, because small parts I used to simply shift course and avoid the loss of these components. I often use two pieces of solder to slide
                    its really confusing why it still shorted even i removed everything in this line...

                    from PQ15, PQ20,Pc136, pc132, pr46, pr47, pq1....
                    Attached Files

                    Comment

                    • Ramee
                      Badcaps Veteran
                      • Jul 2014
                      • 218
                      • Israel

                      #11
                      Re: Toshiba L755-13N no power.

                      Could be shorted everywhere, if that's the case. intel chip responsible.
                      Try to check big coils and those smd caps under intel chip, if they are shorted.

                      Comment

                      • ktmmotocross
                        Boardkiller
                        • Feb 2014
                        • 3578
                        • slovakia

                        #12
                        Re: Toshiba L755-13N no power.

                        if u dont wanna removing capacitors one by one, get a PSU and put some power to that rail to show shorted components

                        Comment

                        • rickybucalan
                          Badcaps Veteran
                          • May 2013
                          • 322
                          • philippines

                          #13
                          Re: Toshiba L755-13N no power.

                          Originally posted by meritosari
                          I still can not understand, if from page 36 to page 41 + vin has a short-circuit, should pq20 on pins 4 and pq15 on pin 3 is also a short-circuit

                          quickly find a short-circuit path usually use a PSU that has a current and voltage limits

                          to isolate pu8 of rail + vin try to lift pr42, because small parts I used to simply shift course and avoid the loss of these components. I often use two pieces of solder to slide
                          tnx guys it look quiet good for now i found and solve the issue for VIN rail. but i still have short in +vtt line.
                          Attached Files

                          Comment

                          • ktmmotocross
                            Boardkiller
                            • Feb 2014
                            • 3578
                            • slovakia

                            #14
                            Re: Toshiba L755-13N no power.

                            vtt is for cpu so remove processor and coil

                            Comment

                            • rickybucalan
                              Badcaps Veteran
                              • May 2013
                              • 322
                              • philippines

                              #15
                              Re: Toshiba L755-13N no power.

                              Originally posted by ktmmotocross
                              vtt is for cpu so remove processor and coil
                              cpu romoved and PL4 including Pc142, pc21, pc143 and pc 139 and its still shorted to ground.

                              it could might be +1.05v line?
                              Attached Files

                              Comment

                              • meritosari
                                Senior Member
                                • Oct 2010
                                • 774
                                • Indonesia

                                #16
                                Re: Toshiba L755-13N no power.

                                How many ohm you call is short, if like 0.010 ohm I think its ok for +1.05V rails
                                Try search on this forum about +1.05 rail

                                Comment

                                • rickybucalan
                                  Badcaps Veteran
                                  • May 2013
                                  • 322
                                  • philippines

                                  #17
                                  Re: Toshiba L755-13N no power.

                                  Originally posted by meritosari
                                  How many ohm you call is short, if like 0.010 ohm I think its ok for +1.05V rails
                                  Try search on this forum about +1.05 rail
                                  im using digital multimeter. checking Caps

                                  when testing in diode mode from ground to pin it reads 0.009v and 0.000v other side.

                                  when testing in continuity mode from ground to pin its beeps both end

                                  in ohms mode it reads from ground to pin 022.5 ohm and 000.0 ohm

                                  which one is the best way to find short?

                                  Comment

                                  • rickybucalan
                                    Badcaps Veteran
                                    • May 2013
                                    • 322
                                    • philippines

                                    #18
                                    Re: Toshiba L755-13N no power.

                                    again after i found shorted caps on VIN line and tested it. it short again this time in PL8 get shorted. lifted up short goes to +3vpcu

                                    removed Caps pc145 and pc226 still shorted.
                                    Attached Files

                                    Comment

                                    • v11
                                      Member
                                      • May 2016
                                      • 44
                                      • Germany

                                      #19
                                      Re: Toshiba L755-13N no power.

                                      Originally posted by ala_borbe
                                      try this


                                      Thank you for schematic....



                                      BR

                                      Comment

                                      • borbooroski
                                        Senior Member
                                        • Mar 2014
                                        • 177
                                        • Ghana

                                        #20
                                        Re: Toshiba L755-13N no power.

                                        who cam help me read all motherboard faulty's i really need help?

                                        Comment

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