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Acer A315-55G / DA0ZAWMB8E0 not charging [SOLVED]

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    #41
    Re: Acer A315-55G / DA0ZAWMB8E0 not charging

    Hi.

    1) Do you have a stable REGN (+6 volts) on your charger IC @ PU1 ?

    2) Any corrosion on this board and area of the logic board ?

    3) Confirm the current sense parts and traces are reaching the charger IC ok.

    4) For the brief 1-2 seconds where ACOK is pulled high -> what voltage is present @ B+ ?

    5) Remove all power and review the resistance across each mosfet pin to confirm the mosfet is not defective.

    Each mosfet linked to this charger IC should be reviewed.

    With no power, meter in resistance mode, check:

    source (1-2-3) & drain (5-6-7-8)
    source (1-2-3) & gate (4)
    gate (4) & drain (5-6-7-8)


    Post the readings for:

    PQ1 (ACFET)
    PQ9054 (RBFET)

    PQ30 (HIGH SIDE battery charge FET)
    PQ29 (LOW SIDE battery charge FET)

    PQ2 (Battery FET)

    Comment


      #42
      Re: Acer A315-55G / DA0ZAWMB8E0 not charging

      Originally posted by vannix View Post
      but without ACOK there will be no ACDRV.
      Not true since ACOK can be pulled up to an external supply derived from the main power rail. So it may not be high before the DC-in MOSFETs are turned on, but it's not necessarily pulled low by the charger IC either.

      Originally posted by vannix View Post
      Without CMSRC there will be no ACDRV.
      As far as I understand it, ACDRV bootstraps at ~6V to turn on reverse protection MOSFET while there's still 0V on source (also 0V on CMSRC), which causes it to start turning on and have current flowing through it, increasing voltage on CMSRC which in turns increases voltage on ACDRV (which should stay 6V above CMSRC), until it's fully turned on and ACDRV reaches DC-in voltage + 6V.
      As indicated in datasheet, if DC-in MOSFETs Vgs < 5.7V for more than 20ms is a fault condition. You'd need an oscilloscope to observe that as most multimeters won't catch it.

      In any case there shouldn't be a need to go to such length as https://www.badcaps.net/forum/showthread.php?t=90356 covers almost all cases.
      One thing that's not covered is that a bad contact in DC-in jack can also cause a voltage drop due to higher current draw when turning on DC-in MOSFETs which will create a fault condition (voltage drops below UVLO) and the multimeter may not catch it either. Bad DC-in jack can also disable charging circuit on some machines.
      Another is a bad buck converter MOSFET for battery charging rail that can pull REGN low.
      Last edited by piernov; 06-16-2022, 06:19 AM.
      OpenBoardView — https://github.com/OpenBoardView/OpenBoardView

      Comment


        #43
        Re: Acer A315-55G / DA0ZAWMB8E0 not charging

        Have posted a thread on the TI forum which you can follow here:

        https://e2e.ti.com/support/power-man...acdrv-question

        Comment


          #44
          Re: Acer A315-55G / DA0ZAWMB8E0 not charging

          Originally posted by mon2 View Post
          Have posted a thread on the TI forum which you can follow here:

          https://e2e.ti.com/support/power-man...acdrv-question
          Thank you very much for your time, i'll check the discussion to see if anyone can give us other important information (now there is an answer but it's not very useful).

          Originally posted by mon2 View Post

          1) Do you have a stable REGN (+6 volts) on your charger IC @ PU1 ?
          2) Any corrosion on this board and area of the logic board ?
          3) Confirm the current sense parts and traces are reaching the charger IC ok.
          4) For the brief 1-2 seconds where ACOK is pulled high -> what voltage is present @ B+ ?
          5) Remove all power and review the resistance across each mosfet pin to confirm the mosfet is not defective.


          1) Regn seems stable at 6v (5,95v) with dc adapter connected. 0v on battery.
          2) No corrosion/water damage.
          3) Each trace and current sense seems to reach the charger ic.
          4) Not always the dc passes the 2nd fet. But in both cases the initial situation is the same. I get about 1v between PQ1 and PQ9054 slowly increasing to about 3v, then:
          option 1: the voltage rises rapidly to 12-15v and B+=12-15v, ACOK goes low.
          option 2: the voltage decreasing slowly to 0v and B+=0v, ACOK goes low.
          5) All measurements result in > 1.5Mohm except for source-drain of pq29 that is 200Kohm slowly increasing to 350Kohm. All fet closes correctly to 0ohm if tested with 2 testers in diode/beep mode.






          Originally posted by piernov View Post
          Not true since ACOK can be pulled up to an external supply derived from the main power rail. So it may not be high before the DC-in MOSFETs are turned on, but it's not necessarily pulled low by the charger IC either.
          In this board ACOK is pulled up by a voltage divider connected to REGN. Then a trace reach the EC.
          Until the EC is not powered there is 0.7v on ACOK, when the EC is powered there is more or less 3.1v.
          I'm sure that the signal is pulled low by the charger ic for 2 reasons:
          1) only the charger ic is powered when the dc don't reach the B+ rail.
          2) i tried to cut the trace between the EC and the voltage divider, and the signal goes from 3v to 0v at the same time.

          Originally posted by piernov View Post
          As far as I understand it, ACDRV bootstraps at ~6V to turn on reverse protection MOSFET while there's still 0V on source (also 0V on CMSRC), which causes it to start turning on and have current flowing through it, increasing voltage on CMSRC which in turns increases voltage on ACDRV (which should stay 6V above CMSRC), until it's fully turned on and ACDRV reaches DC-in voltage + 6V.
          As indicated in datasheet, if DC-in MOSFETs Vgs < 5.7V for more than 20ms is a fault condition. You'd need an oscilloscope to observe that as most multimeters won't catch it.

          In any case there shouldn't be a need to go to such length as https://www.badcaps.net/forum/showthread.php?t=90356 covers almost all cases.
          One thing that's not covered is that a bad contact in DC-in jack can also cause a voltage drop due to higher current draw when turning on DC-in MOSFETs which will create a fault condition (voltage drops below UVLO) and the multimeter may not catch it either. Bad DC-in jack can also disable charging circuit on some machines.
          Another is a bad buck converter MOSFET for battery charging rail that can pull REGN low.
          I had already read your "bible" about the charger ic, i found lots of useful tips in the past (and this is an opportunity to say thank you very much for it) but i don't find nothing helpful for this case. The DC connector is broken, i use 2 wire soldered in the board, so i can exclude this thing.
          The ACDRV bootstrap is an interesting thing that i didn't know. I have an old oscilloscope or a newer (but cheaper and chinese) one, but i was unable to take the moment. I tried with the tester to do some tests (attached). However, the problem always seems to be linked to the too-slow rise of the voltage on B+. If it really works with a "bootstrap" by the +6v REGN the problem may also be due to the faulty bq24780s (already replaced several times) or to the 2.2uf capacitor on pin 24, that i have now tried to replace but without result.

          I'm starting to think that in the fall of the notebook there is the board damaged somewhere and it creates problems in the "24780 startup"...
          Attached Files

          Comment


            #45
            Re: Acer A315-55G / DA0ZAWMB8E0 not charging

            Tiger (TI FAE) has posted full details on the above linked TI support forum.

            1) Inspect the cap on the REGN pin. It is required and is critical.

            2) Remove all power and confirm that both ACFET & RBFETs are not defective.

            3) Once ACDET is confirmed to be > 2v4, Vcc to the charger IC is high enough (19v), REGN will turn ON to supply 6 volts higher than CMSRC to the gates of the n-channel mosfets. CMSRC is zero at the start of this cycle.

            Then ACFET will turn ON and since the gates are common for the first 2 mosfets, so will the RBFET and the AC adapter voltage will reach B+.

            Confirm that the current sense legs of the B+ rail are properly reaching the charger IC so that the charger IC does not feel there is a need to shut down this process which appears to be the case for your logic board.

            Confirm the resistance from each leg of the current sense resistor back to the charger IC. A wrong value will fool the charger into believing there is too much load so the mosfets should be shut off.

            Do review the TI forum thread for a proper explanation from Tiger.

            Continue to post your updates. This is a very good topic to assist in future repairs.

            Update - from a quick review of your last post - replace the RBFET (ie. 2nd mosfet that links to the B+ rail). Confirm the cap on REGN is a good capacitance - replace it if you have another cap that is 2.2uf or higher (6 volt or higher rating).
            Last edited by mon2; 06-17-2022, 05:31 AM.

            Comment


              #46
              Re: Acer A315-55G / DA0ZAWMB8E0 not charging

              Originally posted by mon2 View Post
              Tiger (TI FAE) has posted full details on the above linked TI support forum.

              1) Inspect the cap on the REGN pin. It is required and is critical.

              2) Remove all power and confirm that both ACFET & RBFETs are not defective.

              3) Once ACDET is confirmed to be > 2v4, Vcc to the charger IC is high enough (19v), REGN will turn ON to supply 6 volts higher than CMSRC to the gates of the n-channel mosfets. CMSRC is zero at the start of this cycle.

              Then ACFET will turn ON and since the gates are common for the first 2 mosfets, so will the RBFET and the AC adapter voltage will reach B+.

              Confirm that the current sense legs of the B+ rail are properly reaching the charger IC so that the charger IC does not feel there is a need to shut down this process which appears to be the case for your logic board.

              Confirm the resistance from each leg of the current sense resistor back to the charger IC. A wrong value will fool the charger into believing there is too much load so the mosfets should be shut off.

              Do review the TI forum thread for a proper explanation from Tiger.

              Continue to post your updates. This is a very good topic to assist in future repairs.

              Update - from a quick review of your last post - replace the RBFET (ie. 2nd mosfet that links to the B+ rail). Confirm the cap on REGN is a good capacitance - replace it if you have another cap that is 2.2uf or higher (6 volt or higher rating).
              In these days i have replaced everything possible (in addition to what you suggested) without changes, but from this morning i can say that the problem with probability 99% is not due to the board and not even to the components, but only to the bq24780s.
              This morning i got from a customer another faulty board with 24780s that turns on but sometimes it doesn't recognize/charge the battery.
              I swapped the 24780s, and the problems swapped too.
              Now the pc turns on also with the power supply (all values are ok except for ACOK which is about 9.5v ???) but, sometimes, it stops recognizing the battery and must be disconnected and reconnected (problem described from the customer for the other pc).

              The new ic i had ordered from another seller should arrive in these days.... I'll let you know

              Comment


                #47
                Re: Acer A315-55G / DA0ZAWMB8E0 not charging

                the new bq24780s from mon2's chinese seller has solved the problem.

                while connecting cd jack:
                ACDRV 0->~5v->25,5v
                CMSRC 0->~7v->19,5v
                ACOK 0->3,1v->3,1v

                then stable:
                ACDRV 25,5v
                ACOK 3,1v

                battery is charging, nothing is heating, no strange noises, 1.2-2.5A current draw with windows started and battery charging.


                thanks to all users those who helped me in the repair and (especially) in understanding the operation of these chargers. it will be very useful for next time.
                Attached Files

                Comment


                  #48
                  Re: Acer A315-55G / DA0ZAWMB8E0 not charging

                  Well done and thanks for updating the thread.

                  It is vital that others do the same and not go and hide after the work is done. We have all invested a great deal of time to troubleshoot the defective product(s) - respectively, want this forum to be a knowledgebase for future readers. Only then does it make sense for us to be here.

                  Comment


                    #49
                    Re: Acer A315-55G / DA0ZAWMB8E0 not charging

                    The moderator of the forum should mark a thread "solved" after succesful resolution somewhat like elvikom.pl forum.

                    Comment

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