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820-00850 5v taken not 20v

No-Clean

No-Clean

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Mac was liquid damage but the board is clean, the CD3215 on this board are underfilled so no liquid got under them and all other components around the CD3215 chips look clean. I tried restoring the T2 firmware and also read this post: https://boards.rossmanngroup.com/forum/board-repair-troubleshooting/56483-820-00850-no-20v but I cannot get the board to go into DFU mode and when I try to put it into restore mode nothing happens.

ppbus 12v

pp3v3_g3h 0.019v

At one point one of the ports boot loop but only one time.
 
2informaticos

2informaticos

Administrator
Staff member
"pp3v3_g3h 0.019v"
There is a problem.
Do you get this voltage on two USB-C ports only?
Looks like you have problems in USB-C area, if you don't have the same behaviour on all ports...
 
No-Clean

No-Clean

Member
Yes with 2 of the 4 ports I get 5v on PP20V_USBC_XA_VBUS with the other 2 I get 0v, and with all 4 ports I get 0.019v on pp3v3_g3h

All 4 CD3215 have underfilled and look clean all around them, the liquid did not do any damage or got to the board at all, only near the fan euxast area there was liquid, not sure how this board got to this state with no liquid damage.
 
2informaticos

2informaticos

Administrator
Staff member
So you have 12.28V at F7000?
This could be T2 firmware issue.
Use search function on the forum and try to recover T2 firmware.

However, I'm not sure, as you don't get 3V3_G3H.
Change U6903 first, or check for corrosion on its area; especially R6910-13.
 
No-Clean

No-Clean

Member
Yes I do have 12.2v on F7000.

Here is what I did to restore T2 firmware without success:

1. Mount board on a good top case with battery, connect power button, connect keyboard and trackpad connect/screw battery

2. If you are looking at the keyboard as if you were about to type I connected the charger and USB-C cable to the top left USB-C port

3. Also connected an USB-C Belkin cable on the USB-C port below that one, that same cable I connected to a 2016 15" MPB on the same port location but also tried the other port on the left side with no luck.

4. I opened up Apple Configurator App

5. Pressed and held down Power-Right Side Shift-Left Side Control and Option keys for more than 10 seconds.

But nothing happens on the Apple Configurator App.

About to do the rest you are suggesting.
 
No-Clean

No-Clean

Member
I don't have another U6903 however I reballed it, R6910/13 are both good, I measured them off the board.
 
2informaticos

2informaticos

Administrator
Staff member
"especially R6910-13"
Means R6910/11/12/13...
T2 needs 3V3_G3H too.
This could be the reason of unsuccessful recover process.
Maybe no need to do that, once get 3V3_G3H back...
 
No-Clean

No-Clean

Member
You led me to believe that U6903 was the problem, so I found out that U9080 is the same chip, so I just swaped them and boom got 20v! I now know that U6903 is the problem, time to get some of this chips in stock.
 
No-Clean

No-Clean

Member
I got the TPS62180 chips, replaced U6903, restored T2 firmware and done, Mac is working and customer did not loose any data.

Thanks for your help, I made a few notes on this new MacBooks
 
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