Hello everyone,
I am currently trying to fix a Thinkpad E15 Gen 2 with the motherboard NM-D011.
Initially it was fully dead, no charging lights and charger did not switch to 20V. Replaced the USB-PD-Controller because it seemed to have an internal short and now the charge LED lights up, the battery gets charged but the laptop still does not show any signs of life when I press the power button.
The power button it self is definitely working as it pulls the PWRSWITCH pin of the SIO chip to ground when I press it.
Further troubleshooting reveals that the 5V ALW voltage rail is not switched on, however 3V ALW is present. For the 5V ALW rail to show up, the signals EC_ON_5V an USM_EN_5V both have to be HIGH (that is my understanding after looking at the schematics on page 70). EC_ON_5V is actually HIGH but USM_EN_5V is not, therefore the PowerIC does not turn on. Both signals are coming directly from the SIO Chip.
The BIOS Chip also does not recieve 3V on its input. It gets powered by the 3VALW_PCH voltage rail which has to be turned on by the EC_ON_PCH signal. This signal is LOW.
It did notice however a minor voltage (~1V) on the 3VALW_PCH rail even though it should be turned off. The voltage rail is used as a pull up source for some signals, could that be why there is some voltage on it?
Can anybody explain what the "USM_EN_5V" signal means and why it is not present?
And what needs to turn on first, the BIOS Chip (and therefore also the voltage rail for the bios chip) or the 5V ALW rail?
I am pretty new to laptop repairs and I am not sure what to check next. Any help would greatly be appreciated.
Schematics + Boardview: https://www.badcaps.net/forum/showthread.php?t=106574
I am currently trying to fix a Thinkpad E15 Gen 2 with the motherboard NM-D011.
Initially it was fully dead, no charging lights and charger did not switch to 20V. Replaced the USB-PD-Controller because it seemed to have an internal short and now the charge LED lights up, the battery gets charged but the laptop still does not show any signs of life when I press the power button.
The power button it self is definitely working as it pulls the PWRSWITCH pin of the SIO chip to ground when I press it.
Further troubleshooting reveals that the 5V ALW voltage rail is not switched on, however 3V ALW is present. For the 5V ALW rail to show up, the signals EC_ON_5V an USM_EN_5V both have to be HIGH (that is my understanding after looking at the schematics on page 70). EC_ON_5V is actually HIGH but USM_EN_5V is not, therefore the PowerIC does not turn on. Both signals are coming directly from the SIO Chip.
The BIOS Chip also does not recieve 3V on its input. It gets powered by the 3VALW_PCH voltage rail which has to be turned on by the EC_ON_PCH signal. This signal is LOW.
It did notice however a minor voltage (~1V) on the 3VALW_PCH rail even though it should be turned off. The voltage rail is used as a pull up source for some signals, could that be why there is some voltage on it?
Can anybody explain what the "USM_EN_5V" signal means and why it is not present?
And what needs to turn on first, the BIOS Chip (and therefore also the voltage rail for the bios chip) or the 5V ALW rail?
I am pretty new to laptop repairs and I am not sure what to check next. Any help would greatly be appreciated.
Schematics + Boardview: https://www.badcaps.net/forum/showthread.php?t=106574
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