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Asus FX504 not charging battery

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    Asus FX504 not charging battery

    Hi, I got this Asus laptop as not working. I have found a shorted cap on VIN_VCC_CORE line. I have removed it - laptop started working, showed orange charging LED, but didn't charge the battery and showed it as dead in Windows.
    Then I tried to inject some voltage to battery connector - it started taking charge and then showed as 70% charged in Win and laptop was working on battery, but still didn't charge it. Somebody advised me to discharge it, maybe it need to cycle or something. So now battery is discharged and still doesn't charge...
    I charged it with power supply to 12V directly on the cells, but it doesn't want to take charge over the connector, like it did before.

    I left if plugged over night, so it can catch up, but then I couldn't start the laptop at all. No charging light, nothing. I tried unplugging the battery, AC connector, everything... I left it for a day and it works again on AC.

    I don't have a schematic for this laptop, but I found a boardview for DABKLGMB8D0 here on forum. It's mostly the same.

    Where should I look now? I don't have much experience with laptops, I repair iPhone motherboards most of the time.
    Thanks
    Attached Files

    #2
    Re: Asus FX504 not charging battery

    Originally posted by Roll View Post
    Hi, I got this Asus laptop as not working. I have found a shorted cap on VIN_VCC_CORE line. I have removed it - laptop started working, showed orange charging LED, but didn't charge the battery and showed it as dead in Windows.
    Then I tried to inject some voltage to battery connector - it started taking charge and then showed as 70% charged in Win and laptop was working on battery, but still didn't charge it. Somebody advised me to discharge it, maybe it need to cycle or something. So now battery is discharged and still doesn't charge...
    I charged it with power supply to 12V directly on the cells, but it doesn't want to take charge over the connector, like it did before.

    I left if plugged over night, so it can catch up, but then I couldn't start the laptop at all. No charging light, nothing. I tried unplugging the battery, AC connector, everything... I left it for a day and it works again on AC.

    I don't have a schematic for this laptop, but I found a boardview for DABKLGMB8D0 here on forum. It's mostly the same.

    Where should I look now? I don't have much experience with laptops, I repair iPhone motherboards most of the time.
    Thanks
    check pq27, pq26, pq23 for short (in diode mode). check the signals of pu15 (datasheet is online available), especially the acn, acp, acok, acdet and regn signal. check the resistors and their values (outside of circuit), check mbckl and mcdata signals (3.3 v)

    Comment


      #3
      Re: Asus FX504 not charging battery

      All three mosftets are OK, only PQ27 is connected to ground, as it should be.
      Here is a list of all voltages on PU15 starting from pin 1:
      ACN 18,7
      ACP 18,7
      CMSRC 19,3
      ACDRV 19,3
      ACOK 3,2
      ACDET 2,6
      IADP 0
      IDCHG 0
      PMON 0
      PROCHOT 0 active low
      MBDATA 3,2
      MBCLK 3,2
      CMPIN 0,07
      CMPOUT 0,2
      BATPRES 0 active low
      TB_STAT 3,3 active low
      BATSRC 11,4
      BATDRV 11,4
      SRN 11,4
      SRP 11,4
      ILIM 0,7
      GND 0
      LODRV 0
      REGN 6,8
      BOOT 11,1
      HIDRV 11,3
      PHASE 11,4
      VCC 18,6

      Resistors looks OK, values are mostly the same as in boardview.

      I can't check the signals, as I don't have an osciloscpoe here, I can get one at monday. But the battery reports itself in windows, so I guess it's OK?

      Comment


        #4
        Re: Asus FX504 not charging battery

        Check again the following,

        CMPIN 0,07
        CMPOUT 0,2


        These values are not good.

        If still the same, remove all power, meter in resistance mode.

        Confirm the resistance from the current sense resistor to the charger IC. Same as schematic values?

        Expecting similar voltage to be present for both pins on a good board.

        Comment


          #5
          Re: Asus FX504 not charging battery

          The value change a little bit every time I check. Now it was 0,07 and 0,09 V. They both measure OL on resistance.
          When I checked the line on MB - there was nothing on it, just missing parts. PQ101 and all small parts around are just not installed. Datasheet says CMPIN should be grounded, but I don't think it's the problem, when factory decided not to do it. But I can short it to gnd.

          PR192 and PR214 have 0,1 ohm (minimum my "high quality" mlutimeter can measure), PR220 has 10 ohms as it should

          Comment


            #6
            Re: Asus FX504 not charging battery

            Never mind, found the p/n - datasheet is attached. Had these pins confused with the battery current sense monitor.

            Remove all power -> meter in lowest resistance scale.

            Confirm the resistance for each leg of SRN & SRP back to the charger IC.
            Attached Files
            Last edited by mon2; 03-23-2022, 05:28 AM.

            Comment


              #7
              Re: Asus FX504 not charging battery

              On boardview are two resistors - PR219 and 221, and the line goes trought them. My board doesn't have pads for them. Lines go right under the PR214 (which is 010R). Resistance between SRN and SRP is 0,3 ohm. In diode mode they both measure 532 mV
              Last edited by Roll; 03-23-2022, 06:15 AM.

              Comment


                #8
                Re: Asus FX504 not charging battery

                Be sure to measure the resistance from the actual charger IC pin to the current sense resistor.

                Then repeat for the other charger pin to the other side of the current sense resistor.

                This is important as we have seen a case on this forum - took about 3 weeks to fix - where the trace was broken between one leg of the current sense resistor to the charger IC.

                Due to this fault, the charger IC is unable to gauge the current draw of the battery charge circuit and will shut down the process.

                Comment


                  #9
                  Re: Asus FX504 not charging battery

                  If I understand correctly, I should measure on PU15 (bq24780s) pin 19-20 and 1-2?
                  On ACN-ACP I measure 0,6 ohm and SRN-SRP 0,3 ohm at the chip.

                  Comment


                    #10
                    Re: Asus FX504 not charging battery

                    See attached. Is it the same as yours ?

                    (lost a post here...confirm that VA+ = DC adapter input voltage).

                    Then check the voltage dividers again @ pins 13 & 14.

                    Q: Is PR562 stuffed on your logic board ? If yes, remove all power and measure the resistance. If this part is ~0 ohms then pin 13 is ok @ ~0v.

                    The voltages you have measured are not correct IF the external adapter was connected.

                    See my concerns.

                    reference online calculator:

                    https://ohmslawcalculator.com/voltag...ce6b22bf4b6425
                    Attached Files
                    Last edited by mon2; 03-23-2022, 09:02 AM.

                    Comment


                      #11
                      Re: Asus FX504 not charging battery

                      I will check VA+ tommorow, but I think it is.
                      No, PR562 is not fitted. Everything in that area, that connects to pins 13 and 14 is not fitted on my board.

                      Comment


                        #12
                        Re: Asus FX504 not charging battery

                        So I have charged the battery cells to 12,6V. It showed as 99% charged in windows. Then I left it to loose 10% and tried to uninstall battery drivers, still doesn't charge. It did show white battery light before with AC plugged in, but there is no light now.
                        Now when I plug in charger, it gives 18,73V at the battery connector. That's too much right?
                        The voltages on charging IC are basically identical as before, only batt voltages are little higher, since I charged the bat.

                        I tried to check the mosfets again, but there is no short.

                        Comment


                          #13
                          Re: Asus FX504 not charging battery

                          It sounds like your high side mosfet for the battery charger may be defective since the adapter in voltage is reaching the battery.

                          Remove all power. No adapter and no battery.

                          Meter in resistance mode (2k scale).

                          Check and post the resistance of the following:

                          Source (1-2-3) and drain (5-6-7-8)
                          Source and gate (4)
                          Gate (4) and drain

                          For the high side mosfet for the battery charging.

                          Repeat for the low side mosfet on the battery charger.

                          Finally, check the battery mosfet.

                          Post each resistance check value.

                          Comment


                            #14
                            Re: Asus FX504 not charging battery

                            My multimeter has autoscale. But here are the values:

                            High side
                            S-D started at 30k, goes up to few M
                            S-G 4k
                            G-D started at 40k, goes up

                            Low side
                            S-D 8k, goes up to hundereds k
                            S-G 27k
                            G-D 300k

                            Bat fet
                            S-D 40k goes up
                            S-G 2M
                            G-D 3M

                            In diode mode on high fet S-D I get 750 mV and on low side 920 mV in one direction, 320 mV in other direction on both. Other values are same for both

                            Comment


                              #15
                              Re: Asus FX504 not charging battery

                              I would replace at least the high side mosfet.

                              While sourcing, not a bad idea to also source the low side mosfet as a spare.

                              Test the battery voltage again after the replacement.

                              Comment


                                #16
                                Re: Asus FX504 not charging battery

                                OK, I will also buy charging IC, just in case. Thanks

                                Comment


                                  #17
                                  Re: Asus FX504 not charging battery

                                  I found two AON7410 on spare MB. Datasheet looked simillar (even better), so I replaced both AON7506 and.... it's exactly the same. When I plug in charger, it's volatge jumps about 11-14 V.

                                  Also original charger turns off and refuses to power on until I leave it unplugged for a while. I also have some dumb 19V power supply,
                                  When I plug in battery to powered on laptop, it gives 19 V on battery.

                                  Comment


                                    #18
                                    Re: Asus FX504 not charging battery

                                    When I plug in charger, it's volatge jumps about 11-14 V.
                                    This is better than the 19v posted earlier so the replacement parts are an improvement.

                                    Post the voltage readings on each pin of the battery itself when it is connected to the logic board.

                                    We need to be sure that the SMBUS / I2C interface communication lines are present and not stuck.

                                    Comment


                                      #19
                                      Re: Asus FX504 not charging battery

                                      Sorry for the delay. My friend needed a PC, so he was using it for a few months...

                                      Anyway - voltages on battery connector are -
                                      GND - 0, bat - 11V, P_DATA - 3,25V, P_CLK - 0V DC, about 1V AC.
                                      Also I replaced charging IC, but no change except the 7. pin (IADP) is now 3,3V instead of 0. Still doesn't charge.

                                      I'm starting to think the battery circuit was locked after the cells were discharged (caused by shorted capacitor), and it just need a new battery. Is that possible?

                                      Comment


                                        #20
                                        Re: Asus FX504 not charging battery

                                        Remove all power. Meter in resistance mode.

                                        Remove the battery.

                                        Measure the resistance to ground of:

                                        P_CLK

                                        On the battery connector.

                                        Comment

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