Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

[A1yn88]

Hello everyone, I have attached a diagram for Lenovo C340. I got one in the service with spilled fluids. Initially it was taken to another service where the BIOS was changed, of course it didn't work. The problem is that, although I bought the electronic schematic, I can't figure out why I'm missing + VCC_GT, 0V. If anyone can help me, I would appreciate it. Thanks.

Schematic - https://www.badcaps.net/forum/showthread.php?t=91821

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[stingerchamp]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

If ram section is ok check pin 20 of Pu 501

Check vcc_sa voltage then
vcc_core

Vcc_gt is s0 state high voltage means full on laptop

[A1yn88]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

vcc_sa = 1.010 v
vcc_core = 0.890 v

[SMDFlea]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

Have you checked PUG1 and PQG1

[stingerchamp]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

Check enable pin1 2.5 and pin 8 vcc 5v is coming at RT9610CGQW_WDFN8_2X2 which is generating vcc GT pug1

En pin and vcc both are connected to power on reset logic inside ic and if one goes low output will be low


If enable is low check driven_set is coming out correctly at voltage divider pr272 and pr275

[A1yn88]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

Picture

[stingerchamp]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

First check driven_ set at voltage divider pr275 and pr272

Driven_set must be 2.5v check


Then at core ic puz1 carefully check pin 35 voltage it is driven coming here


Ic will start working when driven is available in threshold

[A1yn88]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

pin 35 = 5V

[stingerchamp]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

Check drven_,set at voltage divider
correction
prz72 and prz75

If 5v then floating is enabled to ps4

[stingerchamp]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

Check prg1 which is 2.2 ohm with 5 percent tolerance
Check pcg1 boot capacitor which is 0.1uf

Enable is ok , vcc ok but pqg1 gate is disabled because ugate supply is missing , boot is the supply for ugate mosfet ,boot supply is not reaching ugate .

[piernov]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

What is the actual issue with the machine?

[A1yn88]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

No video signal, some liquid was spilled.

PRG11 - 2.5 ohm
PCG12 - 0.1 uF
prz72 and prz75 - I don't know where is on the board.
So, the conclusion is the PUG3 is defective because boot supply is not reaching ugate?

[Sephir0th]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

prz72 and prz75 - I don't know where is on the board.

Try to Follow Pin 18 of PUZ1 to find them. They are connected on +5VALW/ Rail.

[piernov]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

Did you check if it's POSTing at least?
If it was liquid damaged you have hints to follow…

[A1yn88]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

How to check if it's POSTing?

[A1yn88]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

No video signal, some liquid was spilled.

PRG11 - 2.5 ohm
PCG12 - 0.1 uF
prz72 and prz75 - I don't know where is on the board.
So, the conclusion is the PUG3 is defective because boot supply is not reaching ugate?

Sorry
PRG1 / PCG1 / PUG1

[Sephir0th]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

How to check if it's POSTing?

Put external Keyboard and Test If CapsLock works.

[A1yn88]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

Not working

[A1yn88]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

First check driven_ set at voltage divider pr275 and pr272

Driven_set must be 2.5v check


Then at core ic puz1 carefully check pin 35 voltage it is driven coming here


Ic will start working when driven is available in threshold

Driven_set = 0V

[stingerchamp]

Re: Lenovo C340 El5c3 el531 el431 la-h101p_lo2 problem

Driven_set 0 is ok because look in schematic @ sign at prz72 means resistor is not populated, only prz75 populated which is connected to ground

Correct me if I am wrong

Core voltage is ok , vccsa is ok

Fault is around pug3