Power Issue with ASUS A705UA.

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  • Christian0734
    Senior Member
    • Nov 2020
    • 92
    • France

    #1

    Power Issue with ASUS A705UA.

    Hello

    The PC starts and shuts down correctly when the battery is removed. However, if I hot-plug the battery, it starts charging as if everything is normal. However, when I turn off the computer and then restart it, there is no display on the screen. The battery indicator blinks slowly, the fan runs, and the power consumption is approximately 520 mA, as if the computer is in standby mode. At this point, even if I disconnect the power supply, the computer doesn't start up normally anymore. Pressing the power button to force a shutdown works, but as soon as I release the button, the computer instantly tries to restart but remains stuck at the same stage as before. The only way to restart it is to disconnect the battery to completely power it off, then plug in the charger. Without touching the power button, it starts automatically and normally, and I can shut it down and restart it without any issues as long as I don't reconnect the battery.

    Note that without the battery, Windows 11 indicates that the battery is fully charged at 100%, even though it's absent. It's also worth noting that this problem doesn't seem to affect restarts because I performed a complete installation of Windows 11 with all updates, requiring multiple restarts with both the battery and power supply connected, without encountering any issues. However, at some point, when I turned off the computer, it failed to restart completely, as I described earlier. I had to disconnect the battery. Furthermore, when the computer is running, if I reconnect the battery while it's on, the computer restarts without any problems. But if I shut it down at this point, it doesn't work. If, at this stage, I disconnect the connector, nothing changes. However, if I disconnect the battery, even without reconnecting the power supply, and then reconnect the battery, the PC starts without any issues on the battery, and this can be done as many times as desired.

    For your information, a colleague has already replaced the battery with a new one, but it didn't solve the problem I described. When he arrived in the workshop, I tested the computer with a fresh installation of Windows 10 and later with a fresh installation of Windows 11. I also attempted to downgrade the UEFI, but so far, EZflash consistently indicates that the file is not compliant, regardless of the version I obtain from the ASUS website. I'm not sure which direction to pursue for a solution...
    Last edited by Christian0734; 09-13-2023, 03:31 PM. Reason: New elements
  • Christian0734
    Senior Member
    • Nov 2020
    • 92
    • France

    #2
    Re: Power Issue with ASUS A705UA.

    Another discovery, I just turned it off while it was running solely on battery. I plug in the power supply and start it up; it starts up just fine. Now, I've started and stopped it 5 times without any issues with both the battery and the power supply connected! In fact, I believe it's completely random, and when the problem occurs, once in I don't know how many times, we have to disconnect the battery to make it work again.

    Comment

    • mon2
      Badcaps Legend
      • Dec 2019
      • 13830
      • Canada

      #3
      Re: Power Issue with ASUS A705UA.

      Review the sticky thread by @Piernov on chargers. Often it is the 2nd DC-in mosfet that becomes defective (leaky) and will raise errors like yours.

      Being Asus, you most likely do not have the schematics? If you do, post or link them in the schematic forum only (not here).

      Otherwise, proceed to review the DC in adapter connector and nearby will be the 2 * DCin mosfets (8 pin) and the charger IC. We need full details on the topside markings of these parts. Then can start the review with a multimeter.

      Comment

      • Christian0734
        Senior Member
        • Nov 2020
        • 92
        • France

        #4
        Re: Power Issue with ASUS A705UA.

        Hello

        As a preliminary note, I must say that I performed about ten startups with both the battery and the power supply connected, and this time I didn't encounter any issues! Nevertheless, I removed the motherboard for an inspection. I'm having trouble locating the two MOSFETs in the main power line because right after the connector, the line goes elsewhere through the board via VIA and doesn't directly come out on the other side of the PCB. However, during the visual inspection, I discovered a melted capacitor. It's not short-circuited, and I tested the two MOSFETs right next to it. The drain of the first one is grounded, which seems normal to m, I believe it's a Buck converter. However, I'm getting an open loop (OL) reading between the drain, gate, and source on both MOSFETs...
        Attached Files
        Last edited by SMDFlea; 09-14-2023, 02:41 AM.

        Comment

        • Christian0734
          Senior Member
          • Nov 2020
          • 92
          • France

          #5
          Re: Power Issue with ASUS A705UA.

          Here is the voltage reading when the board is operating normally. During these readings, the board displays the BIOS on a screen via the HDMI port, and the board's power consumption is around 0.350 A. If I cut off the board's power and turn it back on, the consumption remains around 0.350 A, without needing to press the power button. Just turning the lab power supply to 'on' is enough. However, the BIOS display doesn't always appear. I have to disconnect and reconnect 2 to 3 times for the BIOS to show up, otherwise it's a black screen. (Core-i3 7100U operating at 58° with the heatpipe but without the fan connected.)

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