Hey folks,
i have a Surface Pro 4 1724, that is not willing to charge. The current status is the following:
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:
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):
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.
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.
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:
- i did all troubleshooting mentioned on this link: https://support.microsoft.com/en-us/...ry-wont-charge
- i followed the additional recommendations in here: https://de.ifixit.com/Wiki/Microsoft...roubleshooting
- ran the Surface Diagnostic Toolkit: https://support.microsoft.com/en-us/...nostic-toolkit and everything is OK (even the battery test)
- i opened the device and visually inspected the power circuit (nothing obvious)
- i exchanged the battery 2 times (i have another tablet and a new bought battery at hand)
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.
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