Macbook Pro 820-3115 Logic Board with No Boot. Does have Green Light & Fan Spin

mdc2018

Member
Hello everyone, I am somewhat new to board repair. I can diagnose and repair certain power / back light issues on macbooks, ipads, iphones etc. but am still learning how to use schematics and multi-meter to efficiently diagnose and repair less common problems.

I have this 820-3115 board here for example with no boot. Does have Green Light & Fan Spin (Gradually gets louder and louder until it sounds like an airplane).

This machines did receive light amount of water damage about a week before it started doing this.

* There is no visible corrosion, there are some red probe points around the board.

* I did notice that U3900 gets very hot.

* I checked certain power rails and they seemed to be normal.

* I have multiple known good boards for testing.

I am mostly wondering (based on these symptoms) where I should start and why.

Would be very grateful if someone going point me in the right direction - thank you!
 

dukefawks

Administrator
U3900 getting hot can very well keep the board from booting. But how hot is hot? If it is finger burning hot then the chip is dead at least. It is only LAN chip so can be removed and board will still work.

There is the problem as to how this chip got killed and a voltage spike is one of them, it is not such a good start, high chance of extensive fried chips.
 
Top