Macbook Pro A1989 820-00850 Stucks at 5v. 0.00amp No Boot After Water Damage

Hello again everyone,

Due to your helps and previous posts I have repaired 2 macbooks, and definitely appreciate that Im here with you.

Here is the new story;

A customer of mine brought me a A1989 coffe with milk spilled on it (white and milk without lactose, he said :D :D :D )) and it does not boot up. First I took the board out cleaned the whole board. Changed the components on the corrosion parts. But now on my ampmeter when I plug it I get on 5.192V 0.00A from all Type-C ports.

And I cant see any heating part under the thermal camera also.

any idea where should I start to look? Watched too many videos and read posts but couldn't get any idea. And it is my first time working ona T2 chip macbook.

Thank you for your all help already.

Kind regards

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Diode mode to ground for both lines
PPBUS_G3H 0.004
3V3_G3H_RTC 0.407

Yes there is 5V at R7020

I have checked also PPBUS_G3H line and there is a short but whn I give 12.2V there cant see any heating part on thermal camera. I really cant understand.

When I plugged my ampmeter to my ipower max and adjust the power supply to 20V and 5amp then I find out that UB400 and U3200 gets warm. But cant see anything else which is short on PPBUS_G3H line :(
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Staff member
"I give 12.2V there"
The board may be trash now.
How many threads we have on the forum about this error...

Check if you get similar resistance to ground on any coil; start with CPU coils.
BTW, use ohm scale this time.
I put one side to L7210 1st pad which is CPUCORE_SW1 and other side of my multimeter to F7000 second pad which belongs to PPBUS_G3H line and read on the same mode of my multimeter (resistance Ohm mode) and got 0.003 ohm
and on buzzer mode of multimeter I get signal when I put the multimeter arms to these two components


Staff member
Forget the buzzer, when test low resistance values.
It beeps until 0-50-075, depending by model.

Now, if the resulting resistance between two points is the difference of their resistance to ground, guess what?
The problem is on the common component, connected to both points.
If the resulting resistance between two points is the sum of their resistance to ground, the problem is on other component; connected to PPBUS_G3H and ground (possibly a filter capacitor), in this case.

In any case, don't forget to check all coils in this manner...
Okay I got the idea but while Im trying to understand this idea :) Im a bit confused about the easiest way to find for example that filter capacitor. Because I cant see anything on thermal camera so which is the easiest way to find it my friend?


Staff member
Did you apply power again?
Are you sure is not case explained above?

Using different manner for posting your readings, doesn't help.
I'm pretty sure, you can't read 0.003 anywhere; that means 3 miliohm!
But if you really get miliom value between PPBUS_G3H and L7210, doesn't mean that is short?
You've reported 2.4 ohm and 2.3 ohm to ground respectively.
The difference is 0.1 ohm; one of U7210/20 is burnt...

I considered 820-00850 schematic.
Next time, remember to post board model in the title of new thread.


Staff member
You must lift L7210 one side and check if short dissapears from PPBUS_G3H.
If still short, then do the same for L7220.
You must find which of U7210/20 is burnt...


Staff member
Keep in mind, you've already injected 12V into CPU!
Possibly no repair on this board.
Nothing to lose however; give it a try with new chip.
And don't do same error next time...