Thinkpad T480

Thinkpad T480
Manufacturer	Lenovo
Code name	Windu-2, NM-B501
Release date
Device type	Laptop

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Guides

Device pictures

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PCB pictures

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Reference measurements (also schematics if available)

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More Information/External Sources

Known Problems

An old version of the Thunderbolt firmware present on some machines like the T480 is known for continuously writing to the Thunderbolt flash memory (which is different from the BIOS flash memory). It has previously been though that this will slowly damage the part eventually destroying it. In fact however, the Thunderbolt firmware starts misbehaving once the the EEPROM is full, which doesn't give a chance for the Flash memory device to degrade. Fixing the problem before the laptop starts misbehaving simply involves updating the Thunderbolt firmware to the latest version. After the laptop starts misbehaving the problem can be fixed by using an external spi flash programmer, that can be clipped onto the Thunderbolt flash memory.

The following external sources discuss how to fix this problem:

• https://gitlab.com/MobileAZN/lenovo-t480-thunderbolt-firmware-fixes
• https://libreboot.org/docs/install/t480.html

Notes

• This laptop can still boot if the second phase of the VCCCPUCORE is missing (i.e. if the PU403 dual-mosfet chip is removed). It is not recommended to leave it unpopulated, but the information that it can boot like this is useful for debugging purposes. For example if you have a dead NCP302045 on VCCGFXCORE, and no NCP302045 chips in stock, then you can temporarily steal the NCP302045 from VCCCPUCORE's second phase for testing purposes, to see if it's even worth ordering a replacement part, or if the dead dual mosfet killed the GPU as well while it died.
• If the laptop keeps powering off and on every second or so, with the screen never turning on, it may be because VCCGFXCORE doesn't turn on when it is commanded to. Memory initialization happens before VCCGFXCORE is turned on, so if you remove all memory you will get the no memory beep code, without the repeated power-off/power-ons.

Defects Observed

Please consider contributing by expanding this list, or by incrementing the numbers in this list if you find the same defect.

Defect	Economically Repairable?	How many times observed?
Mosfet on the VCCGFXCORE power rail shorted to VSYS. This blew PL407 with visible scorch marks. Fixing this didn't help, so iGPU probably died from this	no	1
VCC1R0_SUS (PL701) shorted to ground, by PCH. Cracks observed in PCH underfill, but only noticable under microscope.	no	1