lenovo legion y520 dead, 5v power missing

[swammyw]

Hi i need help troubleshooting lenovo legion y520 15ikbn
motherboard nm-b191

first of all i am newbie repairer and thinking if somebody could help me with this laptop what to check

+
20v rail seems ok
3,3v rail also seems ok (pressing powerbutton does nothing but button tested ok and recieves 3,3v)
also SIO recieves powerbutton signal
some caps and resistors with 3v and 1v around SIO can be found but i think all signals are input signals
bios chip also getting 3,3v

-
laptop shows no signs of life
5v rail missing
all coils missing power exept one coil near memory slot 3,3v pl602 +3VALWP

how do i check is the SIO chip gone bad ?
should 5v rail be always present or after power is on ?

[swammyw]

Re: lenovo legion y520 dead, 5v power missing

i measured coils resistance to ground if somebody can take a look does these seem to be correct

pl1401 +1,2v_lx 166Ω
pl3502 +1,0valv 40.8Ω
pl601 +5valp 22kΩ
pl602 +3valp 11.6kΩ
pl201 batsrc 2.6mΩ
pl3501 nvdds 0.04kΩ
pl3402 nvdd 28.4Ω
pl3401 nvdd 27.7Ω
pl1801 1,55vgs 179.8Ω
pl3210 vccsa 16.3Ω
pl3101 vccgfxcore 10.6Ω
pl3102 vccgfxcore 10.6Ω

pl3001 vcccpucore 0.45Ω
pl3002 vcccpucore 0.45Ω
pl3003 vcccpucore 0.45Ω

[mon2]

Re: lenovo legion y520 dead, 5v power missing

pl201 batsrc 2.6mΩ

pl3001 vcccpucore 0.45Ω
pl3002 vcccpucore 0.45Ω
pl3003 vcccpucore 0.45Ω

Above readings do not look healthy. Can you measure them again as a confirmation?

[swammyw]

Re: lenovo legion y520 dead, 5v power missing

pl1401 +1,2v_lx 226Ω
pl3502 +1,0valv 41Ω
pl601 +5valp 43kΩ
pl602 +3valp 16kΩ 3.1v
pl201 batsrc 2.3mΩ 0.01v
pl3501 nvdds 64Ω
pl3402 nvdd 6Ω
pl3401 nvdd 6Ω
pl1801 1,55vgs 174Ω
pl3210 vccsa 10Ω
pl3101 vccgfxcore 6.7Ω
pl3102 vccgfxcore 6.7Ω

pl3001 vcccpucore 2.7Ω
pl3002 vcccpucore 2.7Ω
pl3003 vcccpucore 2.7Ω

thanks mon for taking look @ values, here is some other things i found

pu201 batt managment chip outputs or inputs
5,5v 780s_bs to resistors next to chip
5,8v bq_vdd to cap next to chip

q6 have susp# 4.8v (i dont know what this is)

near sio
ec_rsmrst 0v
ac_present 3,2v
pch_pwr_en 2,3v /disappears & appears randomly but it goes to pch

also sio have very small dent in it could it be broken partially?

[mon2]

Re: lenovo legion y520 dead, 5v power missing

Post a pic of the dent on the ship. It could be the pin #1 dimple dot for the chip.