820-2879 chimes, has backlight - NO image (white screen)

[2andrewd]

Greetings!

Hoping you guys can help me get my head around this one...

LD'd

*restored to s0 state
*chimes on
*have backlight
*screen is initially a warmer "greyish blue" that visibly begins transitioning brighter until finally white

*responds to pram reset

j9000 pins burned (replaced)
u9701 and some surrounding corroded LED return resistors replaced



J9000 w/ internal screen connected reads:


Pin V

1 0
2 3.3
3 3.3
4 3.3
5
6 3.3
7 3.3
8 1.2
9 1.08
10
11 1.18
12 1.07
13
14 1.07
15 1.2
16
17 1.1
18 1.16
19
20 1.6
21 28
22 28
23 0.85
24 0.6
25 0.4
26 0.6
27 0.5
28 0.63
29 0.67
30

Would greatly appreciate any tips or sign posts you could point to.

 

[dukefawks]

Diode mode on all 8 LVDS lines to the connector without LCD connected?

 

[2andrewd]

On j9000 in diode


pin v/drop
8 .769
9 .769
11 .769
12 .767
14 .767
15 .766
17 .767
18 .767

 

[2andrewd]

Swapped out ram and reset PRAM again - now i get image on external and nothing on int, not even bklt, I can't confirm this display as known working though. Would it ruin christmas if a mid 2011 13" air display were plugged in?

Current status:

I attempted to fire up asd but it hangs on "loading videocontroller devices" before fully initializing.
Tried booting into OSX on ext ssd, displays apple and spinning pinwheel loading indicator before hanging. Any ideas come to mind?

 

[dukefawks]

You must use PC8500 RAM. You of course cannot plug in a air screen the connectors are not even the same let alone the completely different interface, LVDS vs. eDP.

 

[2andrewd]

Gotcha. Thank you!