Lenovo Y50-70 not working on power adapter, only on battery

[costivl]

Hello,

This laptop is not powering up with power adapter connected, it only works when battery connected, also it does not recharge battery, i did some checks and i have the following with battery disconnected:

P2 - 20V
VIN - 20,5V
P3 - 0,6V

i replaced PQ302 and i get the same voltages so PQ302 is not the fault in here.

if i connect the battery i get 7V on P3 but battery not recharging.

[emestee]

Re: Lenovo Y50-70 not working on power adapter, only on battery

Can be any number of things but you would start looking at and around the charger IC. Find schematics and boardview if you can.

[costivl]

Re: Lenovo Y50-70 not working on power adapter, only on battery

emestee thanks for answering, what should be the normal voltage on P3 ?

[emestee]

Re: Lenovo Y50-70 not working on power adapter, only on battery

I don't know what "P3" is in your case, I don't know what board is in that machine and you haven't provided the schematics for it.

[costivl]

Re: Lenovo Y50-70 not working on power adapter, only on battery

Board schematics:

https://www.laboneinside.com/lenovo-...matic-diagram/

Check page 47 for PQ301 and PQ302

I also checked PQ301 and PQ302 gate pins and i have 20V on both, it shouldnt be 5v or so?

Let me know thanks!

[lapfix]

Re: Lenovo Y50-70 not working on power adapter, only on battery

The gate of Pq 301/Pq302 are generated by a voltage divider , you must find 8.5v .

what's the voltage at PR311 from the 2 sides .
PU301 voltage on pins : 20/5/6/16.

[costivl]

Re: Lenovo Y50-70 not working on power adapter, only on battery

I forgot to mention i have PR302 removed from board to protect B+ line

Can you please help me locate PR311 on board, let me know if it is this one on the image thanks!

[costivl]

Re: Lenovo Y50-70 not working on power adapter, only on battery

I just found out that on PQ312, S and D was on short, that is why i had 20V on pin 4 of both PQ301 and PQ302, replaced the mosfet and now laptop works like a charm, thanks for help anyway!