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    Acer Emachine La-4854P dead

    I'm not getting any voltage on PIN 5-8 of PQ11. If i jumper from PIN1 to PIN5 of pq11-system boots fine. So rest things are ok.

    So B+ is shorted somewhere but i was unable to find what is wrong.

    PR57/62/65 is ok. MOsfet at PQ10/11 and 12 is ok. I have replaced BQ24751a and checked all resistance near Charging ic.

    Any ideas friends??
    Attached Files

    #2
    Re: Acer Emachine La-4854P dead

    Voltage on pin 2, 3, 4, 5, 7, 8, 10, 13, 21, 28 of PU5 (BQ24751A) when adapter is connected?
    Resistance to ground of B+ line?
    Resistance across PR57?
    OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

    Comment


      #3
      Re: Acer Emachine La-4854P dead

      My suggestion is check PQ10 carefully may be something leakage Drain with Gate...or try to replace this P channel mosfet.

      Comment


        #4
        Re: Acer Emachine La-4854P dead

        pin2-0.5v
        pin3-0.5v
        pin4-19.0v
        pin5-2.61v
        pin7-0.67v
        pin8-2.56v
        pin10-3.96v
        pin13-0.65v
        pin21-0.5v
        pin28-19.0v
        pr57-46.5ohms
        resistance to b+ line-infinity in diode mode.

        Comment


          #5
          Re: Acer Emachine La-4854P dead

          Originally posted by smali View Post
          My suggestion is check PQ10 carefully may be something leakage Drain with Gate...or try to replace this P channel mosfet.
          Replaced pq10/11/12-still no voltage in pin5-8 of pq11.

          Comment


            #6
            Re: Acer Emachine La-4854P dead

            measurements of bq24751a is only with ac adapter connected.

            Comment


              #7
              Re: Acer Emachine La-4854P dead

              Originally posted by mcplslg123 View Post
              pin2-0.5v
              pin3-0.5v
              pin4-19.0v
              pin5-2.61v
              pin7-0.67v
              pin8-2.56v
              pin10-3.96v
              pin13-0.65v
              pin21-0.5v
              pin28-19.0v
              pr57-46.5ohms
              resistance to b+ line-infinity in diode mode.
              According your measurement pin#4 voltage must low ACDRV not working..check pc 45 leakage or shortage.

              Comment


                #8
                Re: Acer Emachine La-4854P dead

                Originally posted by smali View Post
                According your measurement pin#4 voltage must low ACDRV not working..check pc 45 leakage or shortage.
                Yeh pin 4 voltage is wrong ,should be around 12v instead of 19v but I've already checked PC45 and its ok.

                Any further ideads?? This mb is driving me nuts......

                Comment


                  #9
                  Re: Acer Emachine La-4854P dead

                  Check again your fets.

                  Comment


                    #10
                    Re: Acer Emachine La-4854P dead

                    Originally posted by atsio View Post
                    Check again your fets.
                    checked again-not faulty. Still changed them-no result.

                    Comment


                      #11
                      Re: Acer Emachine La-4854P dead

                      Originally posted by mcplslg123 View Post
                      pin2-0.5v
                      pin3-0.5v
                      pin4-19.0v
                      pin5-2.61v
                      pin7-0.67v
                      pin8-2.56v
                      pin10-3.96v
                      pin13-0.65v
                      pin21-0.5v
                      pin28-19.0v
                      pr57-46.5ohms
                      resistance to b+ line-infinity in diode mode.
                      Resistance across PR57 should be 0.015 ohm, check again. If it's way higher than that it may be bad. Don't forget to take into account the resistance of your multimeter leads and the accuracy of the measurement, the reading may be off by a small amount for such a low resistance.
                      Voltage on pin 10 should be around 3.3V, if it's not you may have a defective charger IC.
                      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

                      Comment


                        #12
                        Re: Acer Emachine La-4854P dead

                        Originally posted by mcplslg123 View Post
                        I'm not getting any voltage on PIN 5-8 of PQ11. If i jumper from PIN1 to PIN5 of pq11-system boots fine. So rest things are ok.

                        So B+ is shorted somewhere but i was unable to find what is wrong.

                        PR57/62/65 is ok. MOsfet at PQ10/11 and 12 is ok. I have replaced BQ24751a and checked all resistance near Charging ic.

                        Any ideas friends??
                        let`s keep things simple,first in diode mode measure pq10 , pq11 ,pq12 and reverse black and red probe,

                        should find something like 490V and OL other side.p channel 4407 is easy to find on scratch boards.and let me know.

                        Comment


                          #13
                          Re: Acer Emachine La-4854P dead

                          Originally posted by bachir2004 View Post
                          let`s keep things simple,first in diode mode measure pq10 , pq11 ,pq12 and reverse black and red probe,

                          should find something like 490V and OL other side.p channel 4407 is easy to find on scratch boards.and let me know.
                          Those are very basic things. I have already checked those things before posting for help. Anyway, thanks for your ideas Bachir sir

                          Comment


                            #14
                            Re: Acer Emachine La-4854P dead

                            Originally posted by piernov View Post
                            Resistance across PR57 should be 0.015 ohm, check again. If it's way higher than that it may be bad. Don't forget to take into account the resistance of your multimeter leads and the accuracy of the measurement, the reading may be off by a small amount for such a low resistance.
                            Voltage on pin 10 should be around 3.3V, if it's not you may have a defective charger IC.
                            I have replaced charger ic twice-the last one from a workig board just to be sure. So charging ic is not bad-100% sure. It should be 3.3v on pin10 but i'm getting a bit higher 3.9v.

                            PR57 is ok-i have measured by taking resistance out of the circuit and even replaced it. No result yet.

                            I have removed lan/cardreader/sound ic.

                            Comment


                              #15
                              Re: Acer Emachine La-4854P dead

                              Check the function of PU1( LM358 )

                              Comment


                                #16
                                Re: Acer Emachine La-4854P dead

                                Originally posted by smali View Post
                                Check the function of PU1( LM358 )
                                I have checked LM393 as well as LM358A-no problem found, even replaced them. No luck yet.

                                Client has agreed to take back laptop without charging enabled as his battery is almost dead and he dont wants to buy a new one. So I'm about to deliver it to the client today.

                                Would have been happier if could have solved the case as its always a learning lesson.

                                Still thanks for all your time.

                                Comment


                                  #17
                                  Re: Acer Emachine La-4854P dead

                                  Originally posted by mcplslg123 View Post
                                  I have checked LM393 as well as LM358A-no problem found, even replaced them. No luck yet.

                                  Client has agreed to take back laptop without charging enabled as his battery is almost dead and he dont wants to buy a new one. So I'm about to deliver it to the client today.

                                  Would have been happier if could have solved the case as its always a learning lesson.

                                  Still thanks for all your time.
                                  hello
                                  did you get the solution

                                  Comment


                                    #18
                                    Re: Acer Emachine La-4854P dead

                                    No , I delivered it to customer with charging disabled as customer agreed as mentioned in post#16

                                    Comment

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