820-01987 20v - 1A but no start

[thomamagic]

Hello
Please i need help for the mainboard model 820-01987
I have check and no liquid damage but when i put charger i have 20v and between 0.850A and 1.3A
Fan no Turn, no sound, no picture
Ppbus_g3h 12.6v correct
Cant detect dfu mode

When disconnect battery i have 20v/0.019A

I need help for found problem
Thanks à lot
Regards
Thomas

 

[thomamagic]

Check this thanks

 

[2informaticos]

First of all, welcome to the forum!

Do you get voltage at L7670/90?

 

[thomamagic]

thanks for your message
L7670 : 5v
L7690 : 3.3v

 

[2informaticos]

Any other big coil gets voltage?

Machine should appear in DFU mode.
Be sure to follow all the tutorial steps.
You can check SOC_DFU_STATUS, to make an idea about actual board state.
Try forcing with SE032 pads.

 

[thomamagic]

L7270 : 0v
L7210 : 0V
L7220 : 0V
L7410 : 0V
L7420 : 0V
L7702 : 0V
L8410 : 0V
L8100 : 0V
L7030 : 12.75V
SOC_DFU_STATUS is down U3900 and U3100
for dfu i don't detect
when i push the 4 button, the macbook have 20V but 0.000A

 

[thomamagic]

ok i have dfu mode but impossible to restore, i have error libusrestore error:21 [com.apple.MobileDevice.MobileRestore -- 0x15 (21)]

 

[2informaticos]

Flash SoC ROM (U4770) and try DFU again.
Make backup first.
Be aware, is 1V8 chip!

 

[thomamagic]

arf don't have reader for this, only for bios
can get on donor mainboard?

 

[2informaticos]

If you plan to stay in business with MacBooks, need to get such programmer.

You can try another chip from donor board, same model.
However, should be good to make a backup of that one too.
In case you need to put it back.

 

[thomamagic]

I have buy programmer, receive tomorrow
I have lot but not for this
Thanks

 

[2informaticos]

The programmer itself is not the problem.
CH341A can do the job.
The problem is to get good 1V8 adapter and support board to solder the chip (USON 3x4).

 

[thomamagic]

i have receive, do you have file? or link? Thanks

 

[2informaticos]

A2289 T2 Unlock Data.BIN

drive.google.com

 

[thomamagic]

Perfect thanks i test tomorrow when im office

 

[thomamagic]

flash now and i have same error message

 

[2informaticos]

Error 21 was solved sometimes reflashing SoC ROM.
But may have SSD problem in fact.

Just in case, check diode mode to ground on big coils and SSD power rails.
Also check at Power FETs output, page 74.
Compare readings with good boards.

 

[thomamagic]

what is strange is that I have no display, no ventilation and nothing on the touch bar

 

[2informaticos]

Why strange, if your board doesn't boot?
You can expect these untill CPU starts to work...