Stupid Mistake* made screen unreadable

Sandy McMurray · May 9th, 2005, 10:46 AM

* Who can resist a troubleshooting thread with Stupid Mistake in the title?

Background:
Display preferences in Tiger includes an option to rotate the display 90, 180 or 270 degrees. (This is either an impressive use of the new graphics capabilities in Tiger or a feature I never uncovered in Panther.)

The Problem:
Tiger makes this feature available for some monitors that do not support it. If you select rotation and hit the Apply button, your screen will become unreadable after you make the change. If you do nothing, it will change back after a few seconds, but if you accidentally hit Return while it's unreadable, the screen stays unreadable.

MY problem:
It appears that this option is not only available to advanced monitors that support it, but also to monitors that are unrecognized by OS X (e.g. the very old 14" Zenith monitor I was using with a Mac mini).

And, yes, I did hit Return while it was unreadable. I couldn't remember if the default was "Hit Return now to keep these settings" or "Hit Return now to cancel." I know, I know.

As a result, I now have a Mac that boots but displays only wavy lines. I can't see through the junk to reset the Display prefs.

Simple solution (I thought):
Connect to a different monitor and change the setting back. Right?

Wrong. This only helps temporarily. When I reconnect to the old monitor, Tiger helpfully remembers the screwed up settings and restores them! Argh.

Any suggestions?
Sandy

MacDoc · May 9th, 2005, 10:54 AM

Try resetting the video by Command Option P R and let it go through the reboot twice should clear the VRAM memory.

Also try Command Option O F - then type reset-all to reset the firmware.

Sandy McMurray · May 9th, 2005, 11:35 AM

Neither PRAM reset nor Open Firmware reset removes the 90 turn settting.

Any other ideas?
SMc

MacDoc · May 9th, 2005, 11:47 AM

If you can boot to another screen - you might want to see what files were altered - not sure where the instruction would reside - might need to view invisible files.
Not sure what utility will do that for Tiger - I use Onyx for Panther. Could not find an invisible file solution in Tiger tho a carefully targeted search script might do it byincluding invisibles but not sure if they would be able to be accessed.

You might have to boot off a Panther drive and hunt down the offending pref that way by date. Interesting question.

You could try a deep clean with Cockail tho that's unlikely to help.

MacDoc · May 9th, 2005, 01:21 PM

You can get a utility here to show invisibe files

http://www.mac4ever.de/invisibles/

Look for

com.apple.systempreferences.plist

Chealion · May 9th, 2005, 01:24 PM

Sandy - IIRC, the display settings are stored in a preference file which can be found at:
~/Library/ByHost/

The specific file name is com.apple.preference.displays.(Your MAC Address).plist.

Try deleting this and see what happens.

MacDoc · May 9th, 2005, 01:47 PM

Yeah that looks better - search did not come up with that by date modified only the system prefs.

Don't like the new search - no option for invisible files.

Hank · May 9th, 2005, 01:50 PM

	Quote:			Originally Posted by Sandy McMurray
	* Who can resist a troubleshooting thread with Stupid Mistake in the title? Wrong. This only helps temporarily. When I reconnect to the old monitor, Tiger helpfully remembers the screwed up settings and restores them! Argh. Any suggestions? Sandy

A couple of suggestions.....
•Have you tried booting up in single user or safe mode? This may allow you to access the preferences for the display and reset the condition to something useable.
•Does the monitor exhibit the same conditions when connected to another computer? If yes. Is there a physical reset button that you can push on the monitor to restore it to factory default?

MacDoc · May 9th, 2005, 03:55 PM

Now that's an interesting approach - get a second monitor set up and hit Detect Displays

or even boot up with the display off and then turn it on but second monitor should fix it all.

Sandy McMurray · May 10th, 2005, 12:10 PM

Thanks to all who replied.

Deleting display preferences did not help. Booting in Safe Mode was the right idea but did not fix the problem -- the option to rotate the screen does not appear when booted in Safe Mode. (Argh!)

I thought of connecting a second monitor, but this was a Mac mini, remember -- only one video port available.

I eventually solved the problem by booting in Safe Mode and practicing the steps required to change the display resolution, then rebooting and repeating those steps blind -- like feeling around in the dark.

I managed to locate System Preferences and the Displays preference pane, then selected 640 x 480 which was visible enough at a 90 degree rotation to see the "Rotate" menu. Once this was reset to "Standard" all was well.

My unexpected and unwelcome adventure in advanced display settings is over.
Sandy