(347) 552-2258 [email protected]

Macbook air 820-01521-02 No Backligth, No Image

isa1985

isa1985

Member
This device come to me with not power on.
After fisrt check, I find nothing, no liquid, No drop, USB Activity 5v after 3 seconds 20v.
I was lucky, then I find samge device in my store.
I connect the working board to this devices, and evrything work fine, so I was sure problem is on Board.
Then I connect this Macbook with USB-C to my working one, I start Apple Configurator 2, and this Macbook was detected in Recovery mode, so then I restore it.
After restoring, this macbook look in Apple Configurator 2 not in DFU or Recovery mode, just lock symbol, and finaly i can hear something, the charging ton.
evrytime when I connect the charger wait one min. the I disconnect it, and when I connect it second time I hear charging ton.
mainboard to lcd bridge cable was changed.
USB Activity now, without Battery 20,2V 0.10A and macbook start, cpu fan turn on, but nothing on the screen, no backligth, no image, with HDMI Adapter no Image, ( HDMI Adaptor work woth my working Macbook AIr)
USB Activity now with Battery 20.2V and slowly going up to 1.95A ( 0.10A,0,30A,055A,0,95A,1,45A,1,80A,195A)
I have boarwiever, I have shematic, all tools.
Please try to Help me, I want to make this device, its take so mouch time from me, and please understand for my bad english.
 
2informaticos

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

Changing from 5V to 20V on USB-C meter, doesn't mean USB activity.
You should confirm activity with an USB mouse at least; better using a pendrive with Link LED.
Still get the sound when connect charger?
Try PRAM reset.

Did you try to put it again DFU restore?
 
isa1985

isa1985

Member
2informaticos said:
First of all, welcome to the forum!

Changing from 5V to 20V on USB-C meter, doesn't mean USB activity.
You should confirm activity with an USB mouse at least; better using a pendrive with Link LED.
Still get the sound when connect charger?
Try PRAM reset.

Did you try to put it again DFU restore?
Click to expand...
Thank you.
Please more details about USB activity , you mean that I have to connect USB Flash drive, or Mouse with LED?
PRAM, done, no result.
I have some video uploaded on Youtube
 
2informaticos

2informaticos

Administrator
Staff member
You should get steady light on mouse, at least.
Link LED flashing on pendrive is always the best confirmation.

I'm not sure if I heard the charger detect sound cycling; that could mean machine restarts in cycles.
Try DFU restore again.

BTW, do NOT quote an entire post visible few centimeters above...
 
isa1985

isa1985

Member
So.
Today I replace U8400, I was sure that this the Problem is, but this Macbook still with no image, no backlight.
I put it again IN DFU mode, restore it again= nothing.
But I am sure now, that is no Image signal on screen, before I was sure , I can't see nothing, cause no backlight, but when I disconnect the backlight flex cable from working macbook, I can see easy apple logo, and on this from custumer no Image.
I compare J8500 in diode mode, the pins with number 8,10,14,16,20,22,26,28 show nothing.
All another pins from 1 to 42 it's same, but 8,10,14,16,20,22,26,28 all that show in zero OM.
Second video.
 
2informaticos

2informaticos

Administrator
Staff member
Missing internal/external image at same time is not a problem of backlight, or other internal LCD connection issue.
If you don't get external video, why did you change U8400?
 
isa1985

isa1985

Member
I think when I turn on this macbook, he come Automaticly to Internetconnection,and in this mode External Monitor (HDMI) not work, I checked it on working macbook.
can you give me a tip, what else can i check more?
 
2informaticos

2informaticos

Administrator
Staff member
If you don't get external video, try to confirm USB activity at least.
If not, the board is stuck, not only video issue.

What happens now, if you start again DFU restore?
 
isa1985

isa1985

Member
So, I can say now, I don't have any USB activity.
I don't have external video.
And Caps Lock LED showing nothing
 
You must log in or register to reply here.
Top