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    Microsoft Surface Pro 4 not charging

    Hey folks,

    i have a Surface Pro 4 1724, that is not willing to charge. The current status is the following:
    • charging light is shining white
    • in windows the battery and charger are recognized (plugged in, not charging)
    • there is also no charging when the tablet is shut down
    • all other subsystems work correctly


    This is what i have done so far:

    Then i searched the internet for possible troubleshooting solutions. First tip here is to check the 2 Schottky Diodes (see picture) https://www.youtube.com/watch?v=Qrdfd3Rojxw. In my case they are OK:
    • 0.29 V forward V (the upper one)
    • 0.21 V (lower one)


    The upper one also measures the correct voltage with battery or power adapter connected.

    Next i checked the jumper mentioned here: https://www.youtube.com/watch?v=aMGikVXxdBY. Totally fine.

    Now it was time for a deep dive. I looked up the charge controller (https://www.ti.com/lit/ds/symlink/bq24770.pdf) and did some measurements (from now on i report voltages in the form (without charger/with charger, e.g. 0V/15V for the adapter input voltage):
    • VCC is fine (Pin 28: 7.4V/15V)
    • it creates the charge voltage: 7.7V/8.6V
    • it switches the P-Channel MOSFET that carries the Voltage to the battery on
    • ACOK is high ( 0V/3.3V)
    • not BATPRES is low (as it should be, 0V/0V)


    Now i started to think, that there is something wrong with the batteries, or the spring connections to the battery. So i removed the insulating tape hiding the smart battery circuit on one of them (see picture). There are contacts where the battery input and ouput voltages can be measured.
    • V+ is OK (7.7/8.6V)
    • CLK and DATA have voltage (1.7V/3.3V) but i had no oscilloscope to test further
    • Det and Int are both low (0V, 0V)


    So my question is: What are INT and DET supposed to do and are the voltages on them correct for charging? I tried to follow the CLK and DATA lines and they seem to attach to the charge controller on pins 11 and 12.
    Also I would like to know, if someone has another hint, where to look for with this error.

    Thanks in advance.
    Attached Files

    #2
    Re: Microsoft Surface Pro 4 not charging

    Hi,

    there is a little news about this project. Me and a collegue tried to charge a battery externally. So we supplied 8V to the + Pin of the battery with a Lab Powersupply (if you try this please set the current limit to a low value) . No current was flowing.

    But after we touched the DATA pin with a 8V through a 10k resistor shortly, the battery began to charge. So our guess is, that the battery is good and just needs a signal on the data bus to beginn charging.

    The question is: why doesn't it charge via the board? A voltage is present on this pin, when the AC adapter is connected.

    Any help is very appreciated.

    Comment


      #3
      Re: Microsoft Surface Pro 4 not charging

      Hello
      I have near to this case , I replace SP4 battery , the first one never detected by the device , I tried another on , but unfortunately the device never turned on again on charger or battery , any advice to start ?

      Comment


        #4
        Re: Microsoft Surface Pro 4 not charging

        there is a difference between CLK & DATA line what is you BQ2477__ ? INT and DET may be Battery detected battery IN
        Last edited by piernov; 10-06-2020, 02:37 AM. Reason: remove full quote of OP

        Comment


          #5
          Re: Microsoft Surface Pro 4 not charging

          Hi, I am working on this same Microsoft Surface 1724 which is not powering on at all, history was the battery was buldged up & still was not turning on with AC power adapter, totally dead. The DIODE & all the above mentioned components all seem to be ok. On these two Diode (on the band side) I get 14v, other end 0.72v, & when I check VCC on the BQ24770 (PIN 28 only 0.58v) or on the TPS1285A (VCC PIN 12 only 0.31v) . My question is from where these required VCC voltages are generated & coming from. No short to ground & the all Fuseable resistors are 100% perfect. Any help will be much appreciated. Thanks

          Comment


            #6
            Re: Microsoft Surface Pro 4 not charging

            I Don't have the Schematics for this device right now, and didn't Watched the vids, because actually i'm too busy, but from your description i would Check the the DCIN-Mosfet(s). Usually BQ24770 Voltage will be delivered more or less directly from Adapter. So you should search for the fault at First near the Adapter.
            Last edited by Sephir0th; 02-12-2021, 05:15 PM.
            FairRepair on YouTube

            Comment


              #7
              Re: Microsoft Surface Pro 4 not charging

              Thank you very much for your answer "Sephir0th", appreciate!!! Do you know to check the battery of Microsoft Surface Pro 4. Even a brand new battery shows about 0.53Volts on the battery polarity terminal. Why is it so, is this battery different from an iPad battery??? iPad battery, when checked the voltages on the + & - terminals a pure true voltage is shown on the multimeter. But this battery seems to be totally opposite. Can you or anyone help testing these batteries whether they are good or bad or have any kind of voltages in them?? Thanks in advance.

              Comment


                #8
                Re: Microsoft Surface Pro 4 not charging

                Can't say for Sure in Case of Microsoft surface, but i noticed this behaviour often on Laptops in the past, also when batteries were good.

                So don't worry. If Something Is wrong with your charging Circuit (DCIN Mosfets belongs to it), the battery should Charge again after solving the issue.

                Best regards
                Last edited by Sephir0th; 02-13-2021, 11:35 AM.
                FairRepair on YouTube

                Comment


                  #9
                  Re: Microsoft Surface Pro 4 not charging

                  Thanks Sephir0th., I ordered a brand new Original Microsoft Surface battery, let it come in, once I put it in I will let you know about the progress. Thanks

                  Comment


                    #10
                    Re: Microsoft Surface Pro 4 not charging

                    original battery it has 8v on output when tested from its polarity pins i just confirm it now

                    Comment

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