820-00281- PP3V3_G3H showing 2.2volts [SOLVED]

[Kappy]

I have the above, clean as a whistle no liquid damage at all anywhere on the board.

USB showing 5v.

Checked PP3V3_G3H and it was 0v shorted to ground. Located C7081 to be problem, replaced and now PP3V3_G3H shows 2.2v.

Removed R6923 and pin 1 is 3.42v so that problem is on the board side.

I've checked diode mode the caps around all the CD3215 and they are all 2.2v and 0.33(d)

I've used a thermal camera but obviously as it's not shorted it didn't show anything

Any help in trying to locate the problem.

 

[2informaticos]

Has R6923 exact 0 ohm value?

 

[Kappy]

It's 0.2 ohms

 

[2informaticos]

U6903 goes hot?
If not, you can play with R6910/11/13 to adjust 3.3V, instead of 2.2V.
You can try shorting R6913 first, but may be not enough.

 

[Kappy]

U6903 not getting hot.

Before I start playing with the resistors to try and get 3.42v I thought I would removed R6923 applied 3.42v with 2amp Pin 2 and connected the powerline at the same time and I got 20v Apple logo and boot to the login screen.

I've put R6923 back and it's back at 2.2v. On pin 1 without the R6923 on I get 3.42v

The only thing I have noticed is a missing, i think it's a cap, from the Hall sensor block., but this wouldn't make any difference to the drop , I would have thought.

Any thoughts??

 

[2informaticos]

If you got the machine working in that way, the you must play with mentioned resistors.
R6923 must be soldered of course.
In order to increase 3V3_G3H, you must reduce lower resistor (R6911), or increase upper resistor (R6910).

 

[Kappy]

I don't really want to do that as there has to be a reason why it's dropping to 2.2v and this MacBook once repaired will be going out of the country and I don't really wan to pay the shipping charges back if it goes faulty again.

The only thing that isn't working correctly is the left speaker( when looking at it from the keyboard topside) when you turn the volume up full and play base it cut's out. If you leave it for a while it will come back on again. Apart from that everything else is working... I will continue the search for the dropping voltage...

 

[Kappy]

Found the problem it was D6902 - replaced and now its working again.

Just thought I would share the solution to this.. I applied 3.42v to the system side and reduced the amps to see what was the lowest I would get, this was 0.04amps and made me think that at such a low amp it can't be a problem on the system. I then start to measure from R607 and noticed that when I got to D6902 on one side I was getting 5.12v but on the other it was 3.36v and bingo problem found.