(347) 552-2258 help@rossmanngroup.com

820-01958 shorted cpu or not?

B

Blackmambo90

Member
Hello friends,
Got another macbook air in with liquid damage after another shop...
There was some, minor water sign on the board, however not sure if there was more before the other shop played with it (overall the board do appear clean: no flux etc)

After cleaning and plugging the power, there is 20v and 0.17amps, however there is some strange "clicking"/"cracking" noise coming from the board. Can't confirm from where exactly, but most probably from VRMs. After looking for voltage and resistance on coils, it appear that there is 3 shorted coils and no voltage on them. Cant be sure where those are going since didnt found the board view (any one have them by any chances?) But i presume that those are for the cpu. What is strange is that the cpu get warm witch lead me to belive that those coils might be for something else. Any tips please?
 
2informaticos

2informaticos

Administrator
Staff member

820-01958 X1783 MLB-TKSB.rar

drive.google.com
L7210/20/30 are the coils for CPU core voltage.
What is the exact ohm resistance to ground there?
Only need to measure one channel.
Low value expected as normal, but not sure about the range values in this board.
 
B

Blackmambo90

Member
There is literally 0om... actually i removed those coils to see if the short is on the side of vrms or on the other one, and the short is on the side of cpu but the noise is gone
Would try to inject some voltage to see what will heat up, but my power supply is not here yet

Thanks for the board view!
 
2informaticos

2informaticos

Administrator
Staff member
Nominal voltage for caps is much higher than the CPU.
CPU is first to fail in case of overvoltage...
 
You must log in or register to reply here.
Top