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820-02020 no wifi and crashes after waterdamage

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Fizzl92

Member
Hello,
i am working on an 820-02020. It was waterdamaged and stuck st 5V. I fixed that (Short on V3_S2 near UL000 ). I also fixed other minor waterdamage on UD560, UD550, UC300, Q5240, UP700. After that it turned back on and i could download (via RJ45) and reinstall macOS. But it always crashes after a minute or two. I neede several times to complete the startup setup and now i can enter the OS. There is no Wifi hardware detected and i am wondering if the Wifi IC is damaged and if it can be fiexd as it is married to the board if im right. Or is that the wrong path?
Thanks in advance.
 
2informaticos

2informaticos

Administrator
Staff member
The wifi chip is tied to MLB, no way to change it (yet).
You can try to reball it, in case of accumulated crap underneath.
Check all traces and solders in its area.
 
F

Fizzl92

Member
Ok, Thank you. Ill try to reall it. If it wont work is it possible to use the board without the IC (and without wifi)? I read about this possibility in another forum but not sure if its reliable...
 
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Fizzl92

Member
I was working on this device and encountered some intersting new facts. Maybe this helps point in some direction.

- I cut 3V3_S2 (the previously next to UL000 shorted line) power traces to the Wifi IC (as its easier to undo than removing it and should have the same effect). Still crashing.
-If it crashes it shows a purple screen for 1 second, shuts down and even resets the charger after this. AMP-meter thrning off, automatically restarts beginning at 5V, 20V, boot, crash... So thats some kind of CD3215 (or SMC-like) reset?
-Plugged in if i turn it off by holding Power button for 7 seconds it also resets the charger and turns itself back on.
- Also the Touchbar is not working - even in the OS.
- Last thing i came across it that it also crashes in save mode (its still loading a lot of drivers in this mode) but NOT in recovery mode. I can use Drive-utility, safari and even reinstall the OS (using RJ45 adapter) for hours no problem. So it seems to be depending on a specific driver thats beeing loaded at some point.

You got any idea what could cause this/if i could use this device in any other mode or with another operating system maybe?
 
2informaticos

2informaticos

Administrator
Staff member
Change security settings accordingly and test with Windows, or/and Linux.

Read something more about UL000 (and M1 in general) here:

M1 MacBooks - LogiWiki

We have Apple MacBook and iPhone Diode readings and general fault finding information compiled by the leaders in this area
logi.wiki
You may try to recover it.
 
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Fizzl92

Member
I am not very familiar with there "newer" devices. What settings need to be changed and how to do it? I only once installed windows on a 2017 Touchbar intel device.
Good to hear that the article seems to be a reliable source. I found it last week and cut the power traces to UL000 on 3V3_S2 addordingly to this article on friday but no change unfortunately. Now i hope another OS micht work as it stays on in recovery mode...
 
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