Asus X555LD, not turning on.

[mosfetratus]

Hello,

motherboard was already spill damaged, for about a year. Spill was cleaned, but after opening this i see that many points rotted at specific spot.

Mosfet in the picture is getting 19V: drain, gate, source (the same - 19V). When i connect battery voltage from 1.8 to 3.9V is constantly changing. When i remove battery voltage is solid -19V.

I suspect that ITE it8585e is damaged by loose wifi wire plug, touched and shorted some point. Because i disassembled this laptop to fix no sound from speakers problem. I fixed it: turned on computer, and moments after hearing booting sound i left to other room, when i returned computer was dead. Wifi wire is close to that IC.

No light indication, when connected AC, or both battery and AC connected. No lights.

Voltages i measured, based on repair guide on this forum. PWR button is 3.3V

1. 3.3V 10. 0V 19
2. 3.3V 11. 3.24V 20. 0V
3. 0 12. 0V 21. 0V
4. 0 13. 0V 22. 0V
5. 0 14. 0V 23. 0V
6. 0 15. 0V Points 23-28 is 0V
7. 0 16. 0V
8. 0 17. 0V
9. 0 18. 0V

Not sure if it's mosfet or not. Or it could be ITE it8585e.

This is my first this kind repair.

[ktmmotocross]

Re: Asus X555LD, not turning on.

hope its your last when u not clean the spill

[mosfetratus]

Re: Asus X555LD, not turning on.

hope its your last when u not clean the spill

not mine )

Spill was cleaned by some dude, not by me, and my friend asked mo to fix sound problem.

Spill was cleaned, and this is what it looks like after a year, after "cleaning".


Friend said it was spilled with some alcoholic beverage, but perpetrator was not found, it was left over night until it was noticed.

Computer worked fine with this garbage corrosion, question is why it's not working anymore, i brushed that area myself with technical spirit and tooth brush and it worked until i left the room.

[ktmmotocross]

Re: Asus X555LD, not turning on.

this damage cannot be cleaned. u must resolder traces and pads. that pads and traces on that mosfet is eated by corossion

[mosfetratus]

Re: Asus X555LD, not turning on.

this damage cannot be cleaned. u must resolder traces and pads. that pads and traces on that mosfet is eated by corossion

i get 19 volts both ways. Corroded pins are connected to ground pads, ground pad (basepad) connects to the big trace.

It looks crappy, not sure if it's the problem. Because laptop worked fine even with this corrosion

I attached pdf. file on what I based my measurements.

Measured this dodgy mosfet in diode mode: drain to source - 0V, source to drain - 0V, Gate to source - 0.33V, Gate to drain - 0.33V

[mosfetratus]

Re: Asus X555LD, not turning on.

I'm not a shop or a professional, i'm just a dude with multimeter and a hobby fixing friends and my own stuff. I would like to hear an advice about my problem.

[ktmmotocross]

Re: Asus X555LD, not turning on.

"not sure if it's the problem"

so be sure and make thing right. no hints for crappy worker

[brew99]

Re: Asus X555LD, not turning on.

I would start by looking for any shorted components near that corrosion area (use diode mode on meter). It also wouldn't hurt to remove that MOSFET and test it off the board. I can't tell from the repair guide photo, but are there some components missing that might have corroded off in that area?

Do you have a bench power supply handy? You could use that on 19V at the AC input with current limit set, and see if it appears to draw more current than typical (without switching on). Monitor for any hot components.

You need to start from square one being the Ac adapter input, and follow voltages.

I'm not an expert, but 19V also on the gate of the FET doesn't seem right to me.

[mosfetratus]

Re: Asus X555LD, not turning on.

"not sure if it's the problem"

so be sure and make thing right. no hints for crappy worker

I removed mosfet.

And made a picture, marked voltage on each point.

7.65V is with battery 2.63V is without battery

Without AC, but with battery

Source - 6.7V
Drain - 5.97V
Gate - 0V

No missing components.


I tested some inductors, and i get 5V, 1V, 3V, 2.63V

Boardview code - voltage
PL8801 - 2.61V
Pl8101 - 5.02V
PL8100 - 3.29V
PL8200 - 1.08V
PL8502 - 0V
PL8501 - 0V
PL8301 - 1.36V
PL8003 - 0V

Voltages measured with mosfet removed.

[mosfetratus]

Re: Asus X555LD, not turning on.

At closer inspection, gate is not even connected to anything, because of missing resistor.

Mosfet is completely broken that's why i get 19v on gate. I have no clue if it was working moments before computer turned dead.

Don't know what value resistor should be, to replace.

Ok, i noticed that heatpipe is heating up. I will remove heatpipe to inspect what is heating up CPU or GPU


If it's cpu, does this mean game over, because 1.05VSUS is present for CPU?

[mosfetratus]

Re: Asus X555LD, not turning on.

Ok,

so I removed heatsink and checked who's heating up. DIE that i marked heats up tremendously.

[ktmmotocross]

Re: Asus X555LD, not turning on.

did u injecting voltage to some rail?

check resistance on its voltage rail and check its mosfets for short

[mosfetratus]

Re: Asus X555LD, not turning on.

thats northbridge. did u injecting voltage to some rail?

check resistance on its voltage rail and check its mosfets for short

PC 9100 is short to ground, removed it, still short. Checked other side of the board. Every capacitor on that rail is short to ground, no liquid damage.

Could it be that this north bridge just overheat? Because this laptop was never cleaned or had thermal paste replacement. When i cleaned, there was a layer of dust covering exhaust fan, thermal paste was stock.
Owner of the laptop was complaining about slow operation of computer

PQ9108, pin1 is short to ground

PJP8201 is short to ground

No voltage injected.

Removed PU8200

Removed PQ9108

PQ9108 PCB point 10 and point 9 are short to groud 0 resistance

[ktmmotocross]

Re: Asus X555LD, not turning on.

that corroded mosfet is highside. so i think 19V hits the ic, so it is burned

u must replace it

that why u first need to get rid of corosion

[mosfetratus]

Re: Asus X555LD, not turning on.

that corroded mosfet is highside. so i think 19V hits the ic, so it is burned

u must replace it

that why u first need to get rid of corosion

Ok, i ordered a new mosfet. What value resistor should i add to gate connection?

I found this computer in this current condition.

That faulty mosfet is connected to PQ8803. It think it's fortunate that gate was not connected, could have blown that IC.

But it's for charging. Doesn't explain short to ground with cpu.

tested corroded points of mosfet, not shorted.

[ktmmotocross]

Re: Asus X555LD, not turning on.

ic and mosfet is easy to find and replace so dont bother with it

short is under 3ohm

if u wanna check what side is shorted than remove solder fron PJxxx or remove coil

[piernov]

Re: Asus X555LD, not turning on.

What's the exact resistance to ground on +1.05VS? Does the small die on the CPU package (which is the PCH) heats up right away? Is it burning hot or just warm?

[mosfetratus]

Re: Asus X555LD, not turning on.

PQ9108 pin 1 is 0ohm

PL8200 both sides are 0ohm

Small die need to take few seconds to build up heat, it burns fingers.

[ktmmotocross]

Re: Asus X555LD, not turning on.

did u removed PSL8200 before measurements?

or wiped solder from PJP8201?

[mosfetratus]

Re: Asus X555LD, not turning on.

did u removed PSL8200 before measurements?

or wiped solder from PJP8201?

with removed coil i get on point 2: over 200k ohms, point 1: 0 ohms

I don't have solder wick to wipe that point.