Lenovo T480s completely dead

[Andreasbest]

Hello!
Today i received a T480s that is completely dead, the MB is quite sophisticated from what i'm used to repair (4th and 5th gen) so i need your help before i touch anything.
No liquid damage, no visual damage at all.
All caps in red square are shorted to GND, not sure what and if means something.
I'm all ears
Thank you in advance!

Link to schematic - https://www.badcaps.net/forum/showthread.php?t=81061
.

[khaahk]

Re: Lenovo T480s completely dead

How do you define a short? (In ohms)
Do you have a USB-C tester?

[Andreasbest]

Re: Lenovo T480s completely dead

I set the ohmeter in beep and it's beeping in both sides, when i set it on Ω i get 0.4Ω in one pin and 8Ω on the other.
So propably no short.

If you suspect the charger i have tried multiple but no luck.

[khaahk]

Re: Lenovo T480s completely dead

This model has a known thunderbolt controller issue, the firmware of it gets corrupted. So USB-C tester might give an idea if the USB-C controller is communicating with charger and receiving full 20V. You can measure it with multimeter, but you have to find a spot where to take measurement.
https://support.lenovo.com/ee/en/sol...dates-thinkpad

[Andreasbest]

Re: Lenovo T480s completely dead

Didn't know that, thank you!!
Can you suggest a point for measuments?

[SMDFlea]

Re: Lenovo T480s completely dead

Made a thread a while ago about the thunderbolt issue https://www.badcaps.net/forum/showthread.php?t=82558
https://nadim.computer/posts/2018-10-26-thinkpad.html

[Andreasbest]

Re: Lenovo T480s completely dead

Wow, that's exactly what we need.
Can i do the whole procedure with the CH341A?

[SMDFlea]

Re: Lenovo T480s completely dead

Wow, that's exactly what we need.
Can i do the whole procedure with the CH341A?

I`m not saying thats the issue,neither is @khaahk ,just pointing out a known issue.You can try it though

[Andreasbest]

Re: Lenovo T480s completely dead

Yes i will but can i do it with CH341A or i need Raspberry?

[SMDFlea]

Re: Lenovo T480s completely dead

Yes i will but can i do it with CH341A or i need Raspberry?

You sure can,use NeoProgrammer,Colibri or ASProgrammer software.

[Andreasbest]

Re: Lenovo T480s completely dead

I tried 0 filled TB bios and system MB flashing but no luck at all, it's completely dead, no response at all.
So now we know it's not a bios issue and proceed with measurements i guess.
Any advice welcomed

[khaahk]

Re: Lenovo T480s completely dead

Start with basics as usual, PU201 - VREG3/5, how much current is drawn...
But i suggest to purchase USB-C tester anyways, it is cheap and gives useful info about power consumption.

[Andreasbest]

Re: Lenovo T480s completely dead

i bought one but it will take some days to arrive, meanwhile we must measure what we can.
You want voltage on all pins of PU201 ?

[Andreasbest]

Re: Lenovo T480s completely dead

PU201 has no voltages at all, all 20 pins are 0v

[SMDFlea]

Re: Lenovo T480s completely dead

PU201 has no voltages at all, all 20 pins are 0v

Check the fuses and mosfets, on page 70 .

[Andreasbest]

Re: Lenovo T480s completely dead

PF1 and PF2 are fine.
How should i check the mosfet?

[Andreasbest]

Re: Lenovo T480s completely dead

PF2 fuse reads 5v on both pins, however PF1 shows only 0.4mv.
Perhaps a problem with upper mosfet?

[khaahk]

Re: Lenovo T480s completely dead

PF2 is most likely fuse for USB-C port input and PF1 is fuse for docking port. So it is normal that PF1 is 0.
As PF2 has only 5V you have a problem with USB-C controller and charger not communicating. They should bring it up to 20V. You can try the docking port, does it give higher voltage (on PF1 then). This may be a port problem (visual check?), comm lines to PD controller, PD controller, anything else sitting between them.

[Andreasbest]

Re: Lenovo T480s completely dead

I asked a friend to brink a dock the next days, meanwhile how can we proceed?
Visually everything is perfect, like new.
Charge port is in excellent condition too, i measure 5v in some of it's pins, nowhere 20v.

[Andreasbest]

Re: Lenovo T480s completely dead

Bump