Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

[koby058]

Hi

The laptop power on, fan starts and stop. Power on light remain. But the laptop does not start
Witout ram, no beep.
When off, I see 5v on one coil, but i dont see 3.3
When on, i see 5v, 3.3v, 1.2v, 1.8v

Can you help me inspect it?

[mcplslg123]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

Cpu Vcroe present?? VCCSA present?? DRAMRST# present?? have you flashed bios??

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

Hi, did not try bios, should i first try bios ?

How can i measure those?

attached the board photo

[mcplslg123]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

DRAMRST#-check it on pin108 of ram slot.
Strongly recommend to flash clean me bios and remember to take backup of original file. If you dont have access to bios file, post your backup bios in "Bios Section" and ask for clean me fresh bios.

Vcore coil is located on top side of the cpu-the biggest in size.

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

hi

thanks for reply

I have try a bios and got same behavior.

as i mention the 5v was present but the 3.3v was only present when The laptop is powered on.

now, the 5v also missing and i have a chip that is getting very very hot when i plug the charger

I could not recognize it, attached a photo.

How can i proceed here ?

[mon2]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

https://www.badcaps.net/forum/showpo...1&postcount=12

Part is Silergy SY8386BRHC.

https://www.aliexpress.com/item/1005...d=2Jci72gHwCWo

Attached documents are from another s340 schematic but should be similar to yours.

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

Thank you, Do yo think its related to the absent of the 3.3ALW ?

[mon2]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

Yes. See the another view of the same regulator.

Suggestions:

1) Remove all power -> meter in resistance mode. Check the resistance to ground of PL402 - either side of the inductor.

What is the resistance reading? (and scale used on your meter for this test)

2) Based on your post, if the regulator is hot then it is likely defective. With patience, flux and enough heat and low air pressure -> remove this regulator and check the resistance to ground of the same PL402 inductor.

If the resistance is low then there is some defective component on this rail. If practical, you can lift up PL402 with enough heat & flux but with care so that the PCB pad does not get torn off the PCB. Then measure again. This method will allow you to determine if this regulator or consumer (downstream) rail is the fault of the low resistance.

Better idea...remove the solder blob @ PJ401 -> then check the resistance to ground on EACH side of this removed solder blob. Then you will know if the producer (regulator) or the consumer (downstream) is the reason for this low resistance / root cause of the regulator to be heating up or damaged.

Also...check the voltage levels on EN1 and EN2. Only if they are high (~3v3) then the regulator will turn on.

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

Will take me time, i will update here

If you look on the photo you will see the regulator is blowned

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

Hi, i have replaced this SY8386BRHC from donner board, i hav 4.5v on en1 and 0 on en2, how can i proceed?

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

Where ENLDO_5V3v comes from to pin 9 (EN2)?

[mon2]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

See attached.

1) EN2 = based on 2 resistors acting like a voltage divider. They accept the rather high adapter voltage of ~19V and lower it to a safe value using the resistors to create the EN2 enable signal.

If EN2 = 0v then it is possible that B+ is absent. Confirm it.

2) Check the power path attachment on how the voltage should travel onto your logic board onto B+.

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

since i have the 5vALW can i assume B+ is present ?

if only i can find PR402 and measure it. i can only see pr404 and PC430 both have no voltage and then i see a via nothing on the other side.

I have measured resistance to ground on PC430 and got 0.72M ohm

[mon2]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

What is the resistance across PR404 ?

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

What is the resistance across PR404 ?

40k

[mon2]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

This value does not match the other schematic of the S340 but proceed to post a close pic of the other side of the PCB where PU401 resides.

There has to be another resistor somewhere on this board that is used to enable the EN2 signal.

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

Is this one good?

[mon2]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

Actually meant to flip the board so we can view the bottom side.

Before you do that, check the resistance of each black resistor surrounding the PU401 IC.

Any of them with a high enough resistance to be the part we are hunting for?

[koby058]

Re: Lenovo s340 15IIL FL5C5/FL535/FL435 LA-H103P

I have neasured around and did not find very high resistance, most was up to 120k

Attached other side photo