I just upgraded to a combo drive in my Titanium 550 last night. It went without incident, but now my backlight is dead. I went back in and checked every connection, especially around the inverter and everything is tight. I reset the power manager, I tried reinstalling the old drive, everything.

I can actually use the computer fine if I use it in very bright light, so it is for sure the backlight.

Any further clues? I suspect the inverter or the backlight itself, but is there a way to test before ordering parts?

I'm not sure but i think that the same problem appeared after installing Os X 10.3.9 .
I just upgraded to 10.4 and the problem remain the same.

On my PowerBokk Ti15'1ghz( Mac Os 10.4)

my SCREEN looks like it was turned off, but everything is working perfectly, when i change the monitor resolution i can see (during 2 or 3 sec like a flash) that the lights are fine, and the only way to keep my screen ON is to use a very low luminosity (about 1 or 2 point) , when the backlight exceed 3 or 4 point(click) the screen shut down again,
help me please (is it the video card ram?) I don't know what to do??? thanks

The problem is likely a connection to your inverter board. In the 550, that is going to be located in the far back corner on the same side as the optical drive. If the connections are fine, then you likely need to replace the board itself.

-Bradley
PowerbookMedic