A2289 820-01987 stopped turning on

[Saifulla]

Hello, MacBook 2020, initially it was flooded with the display connector, after which it turned on, but only through an external monitor. After replacing the u8100, the processor stopped turning on and warmed up, put it in its place, which it removed, everything is the same. Where to look? The board starts and turns off immediately

 

[2informaticos]

Why did you touch U8100 if got external video?
Is the RAM voltage controller; you can't get any image, if had problems there.

"everything is the same"
Like before, or after U8100 changed?
Re-check the job you did on U8100 area.

 

[Saifulla]

Checked the same thing. What could be overheated in this area?

 

[2informaticos]

Still not clear if your board has external video now, or doesn't turn on at all...

 

[Saifulla]

The board does not have an external video, the processor does not heat up, I looked at everything in the places where it was doing the work, and found nothing. When you press the button, the fan starts spinning for a second and stops

 

[2informaticos]

Can you put the machine in DFU mode now?

 

[Saifulla]

not

 

[2informaticos]

You did something wrong when you work at U8100 area.

If machine responds now to power button, T2 works somehow.
Did you follow exact steps from DFU tutorial?

 

[Saifulla]

I do not know what kind of dfu tutorial, you can throw it off please

 

[2informaticos]

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...

boards.rossmanngroup.com

 

[Saifulla]

Did everything as it says in the tutorial, it doesn't help

 

[2informaticos]

Something went wrong when replaced U8100.
Probably applied heat affected other areas; maybe corrosion under BGA chips..

 

[Saifulla]

I managed to turn on the MacBook, but there is no image, on the macbook 2020 is the display cable from the macbook 2017 suitable?

 

[2informaticos]

Usually, cables and LCDs can be used for test.
However, ALWAYS check in schematics if the connectors have the same pinout.

 

[Saifulla]

Will the matrix from macbook 2017 fit him? and what could be the reason? L8504 burned out due to spilled water, restored it

 

[2informaticos]

L8504 usually gets burnt because of short inside LCD assembly; classic flexgate issue.
If J8500 was damaged by liquid, many times CPU eDP out is fired.
Sometime still gets external video, like in your case...

 

[Saifulla]

So can I throw a 2017 macbook display on it?

 

[2informaticos]

Why don't you post first, diode mode readings (to ground) on EDP lines of J8500?
Start with EDP_AUXCH_N...

 

[Saifulla]

Can you please tell me which lines you need to call, otherwise so far there is not much experience in this

 

[Saifulla]

on EDP_AUXCH_P 0.260v in resistance mode