No Display. But Working fine on an External Monitor?
I have a MacBook Pro 13" Unibody A1278 2009 model. When it is started, the display does not show up but a background light can be seen and can be controlled with brightness buttons (F1, F2). Everything else works fine and it is right now connected to an external Sony Bravia.
It reached its present condition after several mishaps.
September 2009 - bought
December 2009 - Stepped on it - cracked Front Bezel/Panel. But LCD worked fine with no glitches.
June 2010 - Spilled water on lower half (Keyboard and Trackpad) - Immediately turned the macbook upside down and pressed the power button for some time to shut it down (phew!) - I think that is why the sensor below trackpad turned Pink. But still, the display was working after i had let it rest drying for 2 days.
August 2010 - One fine day, the display started to flicker (On/Off - come and go randomly) and finally the same day it died. Of course a background light was still there which could be controlled by brightness keys F1, F2.
Now what i had achieved so far with it is:
I ordered a new Front Bezel/Panel from iFixit and was going to put it in place of the cracked one but the same day the display died on me (August, 2010) so i had the cracked panel removed and the new panel waiting in box.
Then, on January, 2011 - I ordered a 13" Unibody LCD Panel Glossy from iFixit. I replaced it with the old one but still it did not worked. The LVDS cable used was the old one. Still, no video but still the same background light.
Then, when i could not figure out what was the problem, i decided to call my friend with the same Macbook model as mine. We opened up our display assemblies. So, I had my whole display assembly - new LCD panel with my old LVDS Cable connected to his working motherboard and voila it worked seamlessly. Then, he connected his display assembly with mine and it was the same problem, no video.
I asked this question on MacRumors' Forum and Dadioh was kind enough to reply to it - "Data signals going into the LVDS may be bad". The small fuse is fine and i have 27V at full brightness on the boost diode.
Till Feb 2012, it is working fine on an external display. But the new LCD and front panels are waiting in box to be used.
Any suggestions for fixing it up?
Too bad replacing the screen and video cable didn't work for you. Next cheap step is to replace the Inverter.
Also, look for signs of white residue on the logic board. That's signs of water corrosion. You will need to send the logic board out to a shop so they can professionally clean the board and replace faulty micro parts.