Dear all,
For a friend I'm trying to repair an Acer Swift 3 laptop (SF314-42). I'm not a professional, but have some experience (both as amateur and professional) in working with electronic design and repair of musical instruments.
The issue with the Acer laptop is the following:
It was bought new and used (not heavily) at home for about three years. After normal use, it was put to sleep, connected to charger and left over night (just like any other day). The next morning, the laptop would not wake up from sleep. Instead, when pressing the power button, the power led (blue) would turn on for about 5 seconds after which it would turn off again. No other signs of life (no keyboard backlight, nothing on the screen, etc). The battery indicator showed a fully charged battery (blue light).
After reading on various internet fora about possible solutions, I already done the most obvious things, without success. Here's a summary of my attempts and observations::
> Removed all peripherals/cables connected, except charger.
> Performing a hard shut-down by holding the power button for 60 seconds had no effect on the symptoms.
> Perfporming a battery reset (inserting needle in the pin-hole on the bottom for 5 seconds) had no effect.
> Some magic combination of attempts to do hard-shutdown, battery reset, letting laptop rest, and reconnecting charger had incidental succes for 2 times only (out of many more attempts). In these situations, the laptop booted normally, but the internal clock (time) was incorrect. I was able to back-up sensitive data. I also took the opportunity to upgrade the BIOS/firmware to the latest version 1.11, and this was succesfull. However, when shutting down, the original issue would return.
After these relatively straight-forward attempts, I dug deeper:
> I've tested the charger (Wall-wart) with a digital multimeter, and it puts out a healthy 19V. Works fine.
> I connected a phone to the USB-A port of the laptop and saw it charging from the laptop's battery. When performing a hard power-down of the laptop, the voltage on the USB-A port disappears, and returns after pressing the power button again (without the laptop actually booting). From this I concluded that the function of the power switch to manage power to the mainboard is working properly.
> When draining the laptop's battery via the abovementioned phone charging, I was able to confirm normal battery management function. When the battery becomes empty, and the laptop is connected to charger, it indicates charging (orange led) until full (blue led). Again, confirmation of power systems working normally.
As a next step I opened the laptop and dug deeper:
> Due to the erroneous time of the internal clocked observed during incidental succesful booting, I suspected the CMOS (RTC) battery. I measured the voltage it puts out, and found a healthy 3.15V straight out of the battery, and also on the mainboard where this voltage enters.
> I've tried to disconnect any of the internal peripherals I could (touch pad, finger print sensor, SSD, etc.) without any effect on the symptoms.
> I found the schematic for the particular type of motherboard in this laptop (FH4FR LA-J731P rev 1.0), and inspected the circuitry for powering the RTC and CMOS memory. I was able to confirm the presence of an RTC voltage through-out the circuit. The only doubt I have is about the level of this voltage. The schematic indicates a regulator (U8) being present, with an output of 1.5V, but this part is not populated on the mainboard. Therefore, the actual RTC voltage is higher than 1.5V. However, this seems to be done by design, as I found pictures only of the same type of mainboard, where U8 was also not populated. It does make me wonder: what are the voltage limits of the parts fed by the RTC voltage? Are they not exeeded?
> The most interesting observation done with an open laptop was the following: when the CMOS battery is removed, the laptop was able to boot normally for several times on a row, albeit taking longer than normal to do so (probably because having to reinit the BIOS settings).
After this, I feel I'm stuck. The incorrrect time of the internal clock seems to suggest issues with retaining the CMOS memory, but the power supply for RTC/CMOS seems fine, and I don't know what else I could test/diagnose. So my question to more experienced people here would be: what could be the next step for diagnosing the issue? Any help is highly appreciated!
Kind regards,
Rutger
For a friend I'm trying to repair an Acer Swift 3 laptop (SF314-42). I'm not a professional, but have some experience (both as amateur and professional) in working with electronic design and repair of musical instruments.
The issue with the Acer laptop is the following:
It was bought new and used (not heavily) at home for about three years. After normal use, it was put to sleep, connected to charger and left over night (just like any other day). The next morning, the laptop would not wake up from sleep. Instead, when pressing the power button, the power led (blue) would turn on for about 5 seconds after which it would turn off again. No other signs of life (no keyboard backlight, nothing on the screen, etc). The battery indicator showed a fully charged battery (blue light).
After reading on various internet fora about possible solutions, I already done the most obvious things, without success. Here's a summary of my attempts and observations::
> Removed all peripherals/cables connected, except charger.
> Performing a hard shut-down by holding the power button for 60 seconds had no effect on the symptoms.
> Perfporming a battery reset (inserting needle in the pin-hole on the bottom for 5 seconds) had no effect.
> Some magic combination of attempts to do hard-shutdown, battery reset, letting laptop rest, and reconnecting charger had incidental succes for 2 times only (out of many more attempts). In these situations, the laptop booted normally, but the internal clock (time) was incorrect. I was able to back-up sensitive data. I also took the opportunity to upgrade the BIOS/firmware to the latest version 1.11, and this was succesfull. However, when shutting down, the original issue would return.
After these relatively straight-forward attempts, I dug deeper:
> I've tested the charger (Wall-wart) with a digital multimeter, and it puts out a healthy 19V. Works fine.
> I connected a phone to the USB-A port of the laptop and saw it charging from the laptop's battery. When performing a hard power-down of the laptop, the voltage on the USB-A port disappears, and returns after pressing the power button again (without the laptop actually booting). From this I concluded that the function of the power switch to manage power to the mainboard is working properly.
> When draining the laptop's battery via the abovementioned phone charging, I was able to confirm normal battery management function. When the battery becomes empty, and the laptop is connected to charger, it indicates charging (orange led) until full (blue led). Again, confirmation of power systems working normally.
As a next step I opened the laptop and dug deeper:
> Due to the erroneous time of the internal clocked observed during incidental succesful booting, I suspected the CMOS (RTC) battery. I measured the voltage it puts out, and found a healthy 3.15V straight out of the battery, and also on the mainboard where this voltage enters.
> I've tried to disconnect any of the internal peripherals I could (touch pad, finger print sensor, SSD, etc.) without any effect on the symptoms.
> I found the schematic for the particular type of motherboard in this laptop (FH4FR LA-J731P rev 1.0), and inspected the circuitry for powering the RTC and CMOS memory. I was able to confirm the presence of an RTC voltage through-out the circuit. The only doubt I have is about the level of this voltage. The schematic indicates a regulator (U8) being present, with an output of 1.5V, but this part is not populated on the mainboard. Therefore, the actual RTC voltage is higher than 1.5V. However, this seems to be done by design, as I found pictures only of the same type of mainboard, where U8 was also not populated. It does make me wonder: what are the voltage limits of the parts fed by the RTC voltage? Are they not exeeded?
> The most interesting observation done with an open laptop was the following: when the CMOS battery is removed, the laptop was able to boot normally for several times on a row, albeit taking longer than normal to do so (probably because having to reinit the BIOS settings).
After this, I feel I'm stuck. The incorrrect time of the internal clock seems to suggest issues with retaining the CMOS memory, but the power supply for RTC/CMOS seems fine, and I don't know what else I could test/diagnose. So my question to more experienced people here would be: what could be the next step for diagnosing the issue? Any help is highly appreciated!
Kind regards,
Rutger
! Will do these measurements tonight and report back.
Comment