G4 Powerbook bizarre black screen problem

[Purple Tentacle]

Hello everybody. I was wondering if anybody could help.

I have a 15" 1Ghz Powerbook G4 running OS 10.2.x, with something odd happening to the screen.

When I turn it on, the Apple logo and spinning clock thing appear on the powerbook's screen just fine, but when it goes into the OSX login screen, the screen goes completely black.

I have plugged an external (PC) monitor in, and what happens is that it appears to be using the external monitor as the primary display, completely ignoring the powerbook's screen. Even weirder is that when I go into "display properties", the "application unexpectedly quits"!

To be honest I have no idea if this is a hardware or software error (I hope it's software!), as like I say the grey Apple screen appears just fine, OSX is running OK except when it comes to display properties.

I have also done that "power reset" thing where you hold down ctrl-alt-shift-power, which has successfully reset the machine to 1969!

Tonight I am going to transfer all my files, music etc. to my PC and completely wipe the machine and start again, but if this doesn't work, or if anybody has any better ideas, could you let me know?

Cheers!

[Darkshadow]

Hmm, you should be doing command-alt-P-R instead. The above command resets the PMU. Though that should wipe out the NVRAM as well (which is what the key press I mentioned does... only).

Try deleting the file /Library/Preferences/com.apple.windowserver.plist - it seems to have a reference to the display to use. It might solve your problem. You may have to reset your display prefs after deleting that file; just warning you.

[Zammy-Sam]

Hi Purple Tentacle,
I also think it's a software problem you got there. I have two suggestions:
1. boot into your jaguar installation disk and instead of reinstalling the system run the Disk Utility and repair permissions and disk.
2. Reset the PRAM
Hope these things will fix your problem.

[Zammy-Sam]

Oops, didn't see Darkshadows post. He actually meant reset PRAM instead of PMU. PMU is the power-management-unit, which only affects the battery.

[Purple Tentacle]

Thanks guys, I'll try the command-alt-p-r as soon as I get back home.

I already ran a disk check and apparently it was fine, which was a dissapointment for once.

I'm really not worried about messing with the display settings, especially since I'm preparing to completely wipe the lot and start again!

I assume that this NVRAM reset doesn't affect documents on the hard drive? No biggie if it does, as like I say I'm backing everything up on my PC, but it's good to know.

Thanks for not telling me to buy a new Mac or just send it off to Apple!

Cheers.

[Viro]

Originally Posted by Purple Tentacle

Thanks for not telling me to buy a new Mac or just send it off to Apple!

Don't think I ever remember anyone ever saying that. So don't worry. We never brush people off. Not without good reason anyway

[Purple Tentacle]

Hello.

OK. None of the above have worked at all. I have now reinstalled OSX, wiping out the previous installation, and it's still the same problem.

It even still crashes when I go to display preferences.

Something even worse has happened.... after I did the PRAM zapping, the Apple grey screen no longer appears, just a weird horizontal bar that slowly turns grey that looks a lot like a monitor error, on the laptop screen. So I'm now worse off than before!

What do you guys think? To be completely honest, I'm starting to think it IS a hardware error, although the display prefs crashing is still very weird.

Any more suggestions would be very very welcome, as I may have to give up and pay a ridiculous amount of money to get it repaired. And no, I don't have a protection plan!!

Cheers!

[Purple Tentacle]

UPDATE:

I zapped the PRAM again, and now the Apple grey screen is back.... but still no joy with anything else.

I have formatted the hard drive with zeros, and am reinstalling OSX for something to do.... but I know it won't work.