Another 820 - 00165 A liquid damage, number of issues

Hi,

This one had liquid exposure towards the centre of the board. At least that's all I can see here

Issues:

Slow performance
Fan High Speed constantly
No sound via speakers nor headphones
Backlight goes on and off

I put it thru Crest cleaner as it was quite dirty

After crest sounds seems to be back (some audible regular 'burp' from the speakers) but other issues remain
Cant see anything wrong under the scope

Some readings below:

Q7706

1 8.59v 7.92v switching from one to another
2 8.6v 7.92 same as pin 1
3 8.35v 6.4v jumping
4 8.6v
5 from 0v to 6.2v (variation of values)
6 looks like I am "draining it" will go from 2.3v to 0v every time I put the probes on

D7701

1 8v goes down, then raises up
2 16v and "draining down"

F7700

1 8.6v
2 8.6v

There is a continuity between D7701 and A5 ball of U7701


Please assist
 

2informaticos

Administrator
Staff member
"Fan High Speed constantly"
Usually trackpad board/flex.
Sometime caused by LIO board/flex.
Their connectors can get problems by corrosion too.

As per schematic, p?ns 1, 2, 5, 6 for Q7706 are tied together.
Check if pins 2 & 5 of Q7707 are steady high.

Do you get steady 3V3 at pins 18/19 of J8300?
Also check pin 14 level.
Image always present, only backlight flickers?
 
Last edited:
JohnB8812 Looks like you were right.
Found some replacement io board and cable, just the high fan speed now :D
I will remember to always check with another IO board!

Thank you 2informaticos I will see if I can sort this fan issue now
 
Hi again,

Unfortunately the unit is back, high fan and slow performance only this time.
2informaticos I will test the keyboard flex cable, apart of that, any other things I should check?

Kind regards,
Daniel
 

2informaticos

Administrator
Staff member
I suppose corrosion still affects the board.
Possibly some crap accumulated under SMC/CPU.
You can try heating them untill 180-200 degrees; use only quality flux.
But inspect first for any liquid sign on the board.
 
Ok,
before doing anything else I tried a software solution.
Macs Fan Control seems to be working great. I tied the fan to the cpu core temps.
Any way to make the change permanent or this solution is better?
BTW all temps displayed in the app are below 35 so not sure why the fan kicks in at all :/
 
thank you

OK, cpu heatpipe, cpu proximity, pch die, memory proximity and airflow report 128 degrees Celcius. I am guessing one or more sensores are broken, yes?
 
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