Apple MacBook A2338 / Board 820-02020-A / Stuck at 5v 0.47a / Water Damaged USB C port

zeydullak

Member
Hi,

We have MacBook Pro that has one of the USB C port is corroded. We removed it and put new one. Now both port shows 5v 0.47a. This when the board is removed from the laptop case and batter. Please advise what is the first thing we should do for this case?

Thank you
Z
 

zeydullak

Member
USB C Ports taken from the same model. Exactly same. Connected to the board without connecting board to the battery. Just board, USB C ports and USB charging cable. It shows 5v 0.47a.
 

zeydullak

Member
PPBUS_AON is 8.9v and 3V8_AON is 1.7v. When power connected, board is making ticking sound. I put the board under the thermal camera and I see Q5840 has weird temperature rise on one side. Check the attached thermal picture of the element. Please advise what to do next.
 

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zeydullak

Member
We checked good board with results:

Customer Board: 3V8_AON - Diode Mode to Ground --> 0.14
Donor Board: 3V8_AON - Diode Mode to Ground --> 0.34

Customer Boards: Diode Mode to Ground for PPBUS_AON - Diode Mode to Ground --> 0.48
Donor Boards: Diode Mode to Ground for PPBUS_AON - Diode Mode to Ground --> 0.50
 

2informaticos

Administrator
Staff member
Seems to have problems on 3V8_AON power rail.
Not easy to deal with, as resistance is not so low.

Get a performant IR camera and injecy 4V there.
Let see if you can detect any component with a bit more heat than the rest.
You may need to wait few minutes...
 

zeydullak

Member
We injected the power 1V and also 4V to the power rail and it does use any amps. It is not shorted. What can test else?
 

2informaticos

Administrator
Staff member
I already explained, there is no low enough resistance; to heat anything.
Only a performant IR camera may detect (or not) something, in miliampers consumption.
Some of these cameras can show a 3D temperature graphic, which may help.
 

zeydullak

Member
We observed that the chip U5700 (51C) getting hot. I applied some flux and heat it up to make sure that it sits there fine. After doing that the behavior changed and the chips starts to blink under thermal camera. It was sending pulsing to another chip which is U5340. This chip also pulsing. So both chips pulsing like it detect some kind of short and start over and over again. First USB C ports does not use much amps like 0.03 Mamps. the other one loops from 0 to 0.43 Mamps
 

2informaticos

Administrator
Staff member
Not sure what do you mean with Mamps notation.
If you think about miliamps (mA), you are wrong!
I'm pretty sure you can't measure 0.03 mA (30 microamper), nor even 0.43 mA (430 microamper) on the USB-C meter.

Please use electronic measure notations as required...
 

2informaticos

Administrator
Staff member
Why should I donwload a video into my PC???
Can't you post on Google drive, or other place to see it online?
 
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