820-00426 chiming but black screen

Dozer

Member
Hi friends,

I just got in this device. No damage no liquid spill to see.

it is starting, chiming but nothing to see. External screen is black as well.

First I checked the display. On another machine the display is working good. So Display and Display cable is good.

then I checked for L9410 and L9330, both 0.91V

L8300 has 0V both sides, J8300 Pin 5 has 0V , R8338 has 0V on both sides.

SMC_Lid is 0V

FL8300, 8301,8302 and 8303 are ok.

Need a bit help,
 

2informaticos

Administrator
Staff member
"SMC_Lid is 0V"
Check why.

Disconnect any perypheral device which access this signal.
Check for corrosion around Hall sensor.
 

Dozer

Member
ok, the Lid is working good. I measured on pin 30 J4801 but that is ground, there are 2 pins together, so now its clear. pin 28 is 3.42V opened laptop and 0V closed, that is ok.

@JohnB8812 VPU Vcore should be present if its chiming I think. I measured on L7310, L7320 and L7330 1.82V, USB is active as well
 

2informaticos

Administrator
Staff member
Then your problem is not on the backlight circuit.
You should get image first.

You must get 5V at pins 28-30/J8300 in the first few seconds; even without LCD connected.
At the same time, LCD_HPD should go high; requires internal LCD connected.
If not, PCH will not recognize the internal screen.
 

Dozer

Member
thanks for help. a pity but I still want to try that advice from 2informaticos but customer came in to get the macbook back.
 
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