820-3437 Repeatedly R7122

[G.Beard]

Hi.

History of this board it pretty shit.
Starting with liquid damage, was then fucked up by someone who blasted the BIOS chip, the camera chip and other dumb bullshit.

Went over the board replacing anything that was touched before.

Condition
Quarter fan spin.
R7122 out of value.

Replaced
R7122,
R7121,
ISL6259,
C7122,
C7121,
C7120,
Q7180
Q7130 because it had some crust around it.

Again
R7122 in the 100 Ohms range

Does anyone have any idea what else to try please?

 

[2informaticos]

If I correctly understand, R7122 wnet to 100ohms from 10ohms?
There is no other reason than C7122, or U7100.
I suppose R7120 is OK, 20miliohms...

 

[G.Beard]

If I correctly understand, R7122 wnet to 100ohms from 10ohms?

That's what I meant yes.

I suppose R7120 is OK, 20miliohms...

Yes indeed 0.2Ohms

There is no other reason than C7122, or U7100.

Exactly what I thought but after changing C7122 and U7100 the dam thing did it again!.... I'll try one more time and see what happens.
I can't see any other reason for this problem unless there is a solder blob under U7100. Anyway, I'll try again.

 

[2informaticos]

"Yes indeed 0.2Ohms"
That means 200miliohms!!!

 

[G.Beard]

"Yes indeed 0.2Ohms"
That means 200miliohms!!!

My mistake, missed a digit.
R7120 = 0.02 Ohms

 

[G.Beard]

This time current sense is OK but still quarter fan

 

[2informaticos]

Some voltages?
ALL_SYS_PWRGD?

 

[peterfixit]

check battery and charger current sensing

 

[G.Beard]

Given the state of this board I'm not spending any more time on it.

Many thanks for your help.

 

[2informaticos]

Didn't get PPBUS_G3H yet?