Monitor resolution set too high - can't see screen to reset

Z

zgall1

Registered
I set my monitor to display a resolution that it does not support and now I am unable to reset it since the screen is black. What can I do? I've tried starting up in safe mode (holding down shift) but it still starts with the resolution that is too high. I've also tried resetting the PRAM but that does nothing. Lastly, I tried to start in target disk mode but my computer (Quicksilver G4 tower) will not start up in that mode. The Powerbook I am using will start up but that is pretty useless for my purposes as I need to do it in reverse. I know which file I need to delete but I simply cannot access it. Any suggestions?
 
Can you get into single user mode by pressing command (aka Apple) - S on startup? If so, then you may be able to delete the display preferences and restart.

I believe that the commands you would need are:

cd /Users/<your_username_folder>/Library/Preferences
sudo mv com.apple.systempreferences.plist systempreferences.bak
 
Try and hit the PMU reset button. Shut down the Mac and open up the case to access the PMU reset button. It's located inside your G4 tower and it's to the inner right of the motherboard. HIT IT ONCE QUICKLY AND ONLY ONCE! Once you've done this, close everything up and power up your Mac. Hopefully this should reset the video.
 
Boot into Open Firmware holding Apple-Option-O-F keys and then typing in the following commands once you get the screen that says "to continue booting"--

reset-nvram (hit return)

set-defaults (hit return)

reset-all (hit return)
 
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