No Screen Backlight (black screen) , video is OK

Hello !

my precious laptop, has the "black screen" problem,

external monitor is working properly,

I'm leaving in Greece and unfortunately after the economical crisis its not easy to give

the macbook for repair to the authorized service shop... there also so many

complaints for theie service (they are not an official Apple Store but a Reseller )

All started with the a broken left Option key... (which was stuck all the time)

I has to finish my job so I did the "clever" thought to "deactivate" the key by

cutting the metal connection under the key.

Result => Left Option + Control are dead ==> Power up with Power button

is now history.

I was trying to have the macbook always charged and in sleep mode,

and 4-5 times that was out of battery i did the trick with the power-on pads.

After the last power up with the power-on pads the screen is always black

the video is working good but No backlight.

I tried the NVRAM reset without any change.

SMC reset is not possible since I'm still waiting the keyboard from UK.

I found from this forum that my macbook has the 820-3115-B board.

I found the schematics and after studying hard this forum. i tried to locate the

problem of the board.

I'm a software guy (soft enough to get cuts from printer papers..) so its no easy

to follow the hardware jargon...

Anyway I have the following measurements:

The backlight fuse F9700 looks OK about 12V for each pin.

PPVOUT_SW__LCDBKLT_FB has almost 0V !!

The pins of LVDS connector I think are clean enough...

I send a picture of the area, Y9701 (LP8550) looks a little strange i think

(the color turns to black)

I had many problems with overheating of the bottom side ..

(the CPU was running high always due to some demanding processing)

and I can see many metal areas with red and dark color,

last year I'm using Macs Fan Control and the temperature is a little better..

I will try to find a service shop to replace the LP8550 ...

My question is the following :

If for some reason the WLED replacement goes bad .. is it possible to loose the whole

board ?

I mean I can work now with an external monitor , is it possible any failure to turn dead

the whole laptop ?

The photo is not so clear ... sorry ...