Lenovo T480s No power. Heat indicated.

[Andreasbest]

Hello.
One of the T480s that i have here is dead, i noticed that PU404 and PQ101 are getting very hot.
I checked the caps around PU404 but no luck.
Any advice?

Schematics: https://www.badcaps.net/forum/troubl...b471#post72970

Thank you!

[RandoomStyle]

Sounds like a short to me, try to measure resistence on Mosfet, mostly the problem is that.

[Andreasbest]

I indicate no shorts on PQ101. All pin combinations result in many kΩ and ΜΩ measurements.

[Andreasbest]

Boardview too
https://www.badcaps.net/forum/troubl...85#post3319885

[mcplslg123]

Resistance to GND on PL406?

[Andreasbest]

I'll be back to the bench on Frinday, i'll take the measurement on PL406 then, meanwhile i forgot to mention that all 4 caps that you see around PU404 are all indicating short in both pins, i desolder them all but the short remained.
That's a clue i guess?

[RandoomStyle]

Yeah i can check in a couple of hours but yes its a clue, depend where the caps are connect you can check what via it is in the schematic and trace it

[RandoomStyle]

Oh you can check the reference of those caps you removed? i cant see it on the picture

[Andreasbest]

Oh you can check the reference of those caps you removed? i cant see it on the picture

Sure, check below. Keep in mind that i resolder them, there was nothing wrong with them, the short is elsewhere.

[Andreasbest]

PL406 resistance to GND = 7Ω

[RandoomStyle]

With that info on the caps i can see you have a short on VSYS15, you can start desoldering one side of PL405, and measure on what terminal de short remains, if the short is on terminal 1 then you have a problem in other side of the board (Maybe you can focus on the part of PQ101), and if remains on terminal 2, then could be the IC PU404