820 2936 chimes, backlight present but lcd is black

[justin35]

It came in with dimm green light, liquid damage...
Fixed green light, bios chip was knocked off the board.
Replaced lvds connector and lcd backlight fuse.
I took out bios chip from a donor 2879 board without reprogramming it...
Now it chimes and fans spins.
Lcd blcklight voltage is 27.2v on d9701
I can see the backlight comming on the screen but screens remains “black-ish”
Can’t see any logo or question mark folder lighting with flashlight from the back of lcd...
I tried 3 screens all known working, same result...
Any ideea where to look?

Thanks!!

[piernov]

Re: 820 2936 chimes, backlight present but lcd is black

You waited for like a minute or so?
Try a USB drive with macOS on it and check if its activity LED blinks.

[justin35]

Re: 820 2936 chimes, backlight present but lcd is black

Yes, i tried, it has activity, but the screen is still black

[justin35]

Re: 820 2936 chimes, backlight present but lcd is black

See attachment, laptop off very dark screen
Laptop on screen dark/blue

[piernov]

Re: 820 2936 chimes, backlight present but lcd is black

Try PRAM reset and try with external display.

[justin35]

Re: 820 2936 chimes, backlight present but lcd is black

I think it has some issues with keyboard also, i tried pram reset but it won’t do it...
I will flash new bios in minutes and see if it helps...

[justin35]

Re: 820 2936 chimes, backlight present but lcd is black

New bios 820-2879b didn’t work (although my board is 2879a)
Pram reset didn’t work...
I think it’s some bad trace from or to lvds connector?!?