Lenovo legion y540 15irh

[justin35]

Need help !
Lenovo legion y540 15irh
It frozen and didn’t power on after hard reset.
It has been take to a local shop where they butchered the bios ic and gpu bios ic, and they heated pch (hm370)
Now my turn:
Tried bios with new bios but fund out i had a short on 1.05(pch)
I took out pch and reball it
No more short (pch) and i get cpu vcore and gpu vcore but the button light is flasing constantly…. Sometimes it powers off itself (i guess because of thermal cause as i only hve a small radiator in cpu)
Anyone know what this constant flasing power button means?

[mon2]

Re: Lenovo legion y540 15irh

Found this...

https://www.ifixit.com/Answers/View/...board+blinking.

[justin35]

Re: Lenovo legion y540 15irh

Insaw that also, but it doesn’t have anu “ modem” or i am no aware of…

[justin35]

Re: Lenovo legion y540 15irh

I’ve seen an yt video with someone fixing this laptop and after replacing sio chip it booted and during boot the power button led was flashing all the time…
It makes me think it’s normal maybe?!? But why no picture on internal or external display?!?
I will assemble the laptop back and see if it charges the battery or something

[mon2]

Re: Lenovo legion y540 15irh

Huh? Nothing about a modem.

The thread mentions issues with the battery or charging circuit.

[justin35]

Re: Lenovo legion y540 15irh

Here’s what i read from the original author:
“Update (06/28/2020)
Well problem is probably solved, partially. I took out recovery modem and for now it runs. No booting problem for now”

I think i need vga bios as i don’t trust what’s inside that chip

Device: laptop
Brand: lenovo
Model: legion y540 15irh
Board number: nm-c221 rev 2.0 (fy5151/516/517/518/523/524/525/526
REQUEST: BIOS + VGA BIOS
it's important to get the vga bios since someone messed up with this ic....
dedicated graphics - n18e g0 a1 (gtx 1660)

[justin35]

Re: Lenovo legion y540 15irh

Will y740 15irh with 1660 vga bios work on y540 15irh with1660?

[justin35]

Re: Lenovo legion y540 15irh

tried, but without luck...
I have news, laptop is not brain dead. if i press the power button it does the boot sequence.
some fan speed + keyboard baklight
then it restarts and goes to full fan speed
meanwhile i attached an external keyboard and i toggleled capslock and numlock. they work, but after like 20 seconds the laptop goes off
i connected internal screen (no image)
i connected external hdmi (no image)
i plugged in battery and it shows orange light and i think it's charging it...
it even starts from battery only....

[mcplslg123]

Re: Lenovo legion y540 15irh

At post#1, you mentioned you had a short on +1.05V rail(PCH). What is the resistance now after reballing PCH. Wondering how short was removed by reballing PCH.

[justin35]

Re: Lenovo legion y540 15irh

Recently lenovo started to use some sort of glue that acts like an under fill around the bga chip corners…
You cannot reflow the larger bga chips in this case. It will result in a partially desoldered chip, or worse bridged balls underneath.
In my case someone tried this reflow method and resulted in a big short underneath pch (1.05, 3.3 and 1.8v)
I don't know exactly what is the resistance on 1.05v now, but the lowest resistance on pch is around 40ohms and the rest are in hundreds to kohms…

[justin35]

Re: Lenovo legion y540 15irh

Got some new updates:
Board charged the battery and the orange light is off now.
Also the blinking white led it a solid white. It means the flashing power led / button is indicating the battery is not full…
I think at this point the board is working somehow as i can power on/off
It’s not displaying anything on internal or external monitor… i don’t know the cause…
After around 30 seconds it turns itself off. Might be the pc is displaying some warning and if nothing is happening will turn itself off…
I might need to try some bioses and make sure the video bios is correct…

[justin35]

Re: Lenovo legion y540 15irh

Here's what i did so far…
Reball pch
Reball gpu
Reball vram (and change 3 of the banks as i didn't like the way that measure)
Now i have this and i bet is a dead gpu… after all this work, i think i'll get a replcement gpu…because i spent too much time and i need it to work

[mcplslg123]

Re: Lenovo legion y540 15irh

Getting a genuine new replacement GPU is very difficult. The issue could be VRAM chip as well. So suggested to replace GPU along with VRAM,if available.

[justin35]

Re: Lenovo legion y540 15irh

Thanks for your advice! But, vram is ok as long as i took off the vram bank that was pointed as faulty. It turned out to be a not connected pad underneath gpu… i am sure i didn’t screw up anything when i reball it. It might be a broken trace in gpu pcb (not the first one i encounter)
From my experience, samsung memory fails quite rarely