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No backlight during boot!

I

iprashant.menon

macrumors newbie
Original poster
Mar 3, 2010
20
0
It seems my backlight is off during boot. I turn on my MBP and there's a black screen for 30 seconds, no Apple logo & gray screen with spinning wheel, then suddenly it's in OS X. If I <option> boot to Startup Manager I can press the <right arrow> button and click enter to enter Windows through bootcamp.

Any ideas?

I've tried resetting PRAM & VRAM & held the power button down for 5 seconds as well.

I really, really don't want to have to do a clean install.

Help!

Edit: If it helps, I recently configured both Windows and OS X to use an external monitor as the primary, I wonder if that could have complicated things, these problems occur regardless of the ext. monitor is connected or not.
 
I'm not sure about this, but maybe your backlight is off, and then when it boots into OS X, it detects (via Ambient light sensor) the ambient light and adjusts accordingly.
 
That happened to my old MacBook. I shined a torch on the screen and the computer was going and starting up fine - But no backlight! I tried the brightness and that didn't work. Although after a few restarts it corrected itself ;)

BTW: Your saying no backlight during boot. Does that mean the backlight comes on once the machine starts up?
 
Yup, only during boot, the backlight comes on after boot. I'll try that torch trick to see if it really is the backlight or some other problem.
 
So..

So I guess it's not the backlight, tried the torch and I couldn't see anything. Basically I just get a black screen till OS X finishes boot and if I try to boot to Startup Manager, I get nothing but I'm still able to load my bootcamp partition by navigating to it with the arrow key & then hitting enter.
 
I tried installing Refit to see if Refit boot option menu would display after the chime but that didn't work either.
 
Look in the system's library folder and delete the screen preference plist. If your volume level also defaults to a certain level after every reboot that would for sure mean that my suggestion is correct, however, it isn't necessary that both brightness and sound plists have the wrong permissions set.
 
So, your saying that your computer screen doesn't come to life at all until it goes into Mac OSX. Thats pretty strange. Does it do the same on shutdown too or just startup?
 
I finally fixed it. Basically after I connected my ext. monitor I had it set up to be my primary display. OS X & my Windows 7 partition were smart enough to figure out that when the ext. monitor wasn't connected, the laptop's display was to be primary - but the problem was that before OS X or Windows could boot, there was nothing in Apple's startup manager or system to make that kind of adjustment. So if you want to use an ext. monitor with your Mac as a primary display, remember to make sure to reverse the settings in system pref. before you disconnect your ext.

edit: what was weird was that when I tried to boot up before with the ext. monitor connected, I still got black screens on both displays. Apple should sort this out.
 
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