A Dead Laptop With Water Damage Issue Repaired. Model: Asus X556UJ
A computer technician brought his laptop for repair. He said that he got this laptop ten days ago and the issue was water damage. He cleaned it and was able to get it fixed. Later on that week, it came back to him and this time it was completely dead.
It was already taken apart. I took the mother board for inspection and as it is seen on this housing,
there are spots of where the damage was if you look closely you can see it very clearly.
I put it under my microscope for a closer look and I was still able to see water damage that was not cleaned the way it should be.
These marked areas suffered liquid damage and it was seen only under the microscope and not with the naked eye.
There was more water damage on the other side of the board. I could not apply any power to the laptop before cleaning the board. I do not have an ultra sonic cleaner yet but it is on my future shopping list and I should get it soon.
I used alcohol and a tooth brush and gave it a very good clean. The outcome was great but when I finally powered up the laptop, it was still dead. At this point it was clear to me that something was damaged on that board that needed my attention.
I powered the device again and followed the 19 volts rail and soon enough I found what was wrong. The switching Mosfet M0930 was damaged. It was getting the 19 DC volts but nothing was coming out of it. I made a bridge and by passed that Mosfet and this time I powered it through a current limiter and this what I got. Take a look.
The laptop came on and it was working fine. These first two Mosfets are for protection and the part did its job to protect the laptop from further damage. The main problem I did not have the same part in my shop for replacement so I called the computer tech and I explained the situation. The computer tech contacted his customer and explained the situation as well and the customer was willing the take the computer the way it is (by pass the first Mosfet).
The computer tech came and picked up the laptop along with other stuff I repaired for him and was pleased with the outcome.
Mission Accomplished.
This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.
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Note: You can check his previous article on Welding Machine Repair- Repaired But Ended Up With A Bad Argument With Customer
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Parasuraman S
December 3, 2022 at 8:22 am
Very professional fault finding! Well done!
Waleed Rishmawi
December 3, 2022 at 3:21 pm
Parasuraman: thanks man. have a blessed day
Tayo
December 3, 2022 at 9:43 am
Very good repair. Lucky the issue was so close to the AC input.
Waleed Rishmawi
December 3, 2022 at 3:22 pm
Tayo: yes but even if fault found deeper in the board, it would be more difficult but will be repaired. have a blessed day
Albert van Bemmelen
December 3, 2022 at 2:29 pm
Good thing that you not also needed to clean any water damage under the memory chips onto which the yellow arrow was pointing, because cleaning those bga soldered chips would be close to impossible and not without risk! I remember having fixed that same defect N-channel M0930 mosfet in an asus x555ld laptop. First by bypassing it but afterwards replaced it by a new one. Five of those can still be ordered for around 5 dollar including shipping here
Waleed Rishmawi
December 4, 2022 at 8:12 am
The customer did want the mosfet replaced although I was willing to order the parts and doing it for him. Actually I cleaned the area marked with yellow arrow. It had some liquid all over it. Have a blessed day.
Albert van Bemmelen
December 3, 2022 at 3:05 pm
PS: if the laptop battery no longer charges after the bad M0930 is bridged over, that is because of both mosfets that together also take care of charging and protecting the battery pack.
Waleed Rishmawi
December 4, 2022 at 8:12 am
Alber: it was charging just fine. Have a blessed day
Albert van Bemmelen
December 5, 2022 at 1:42 pm
That likely depends on what mosfet of both was defect and bridged over like in the mentioned Asus x555ld laptop.
Yogesh Panchal
December 5, 2022 at 10:47 pm
Good job! Waleed
Waleed Rishmawi
December 7, 2022 at 11:26 pm
Yogesh: thanks man.