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View Full Version : Blanked screen from wrong resolution selection, help.



levelbest
10-01-2007, 04:03 PM
I was playing with the screen resolutions as my Sigma graphics monitor has been showing some odd screen dimensions (before a new memory stick so I don't think that was the culprit). Normally if you choose a resolution that can't be seen it defaults back to the last setting in case you can't read the screen. (Using my 1.25 DP MDD withn Tiger (10.4.9))

Mine didn't return to a view of any kind, it just created a blank screen. The screen is not usable to me at this point. SO I am asking for any knowledge about using single user mode (which I can still see on boot up) to reset to a correct screen resolution.

SO far all I am finding on Google is Darwin project help that refers specifically to something called GRUB and other X11 installs (Darwin Boot loader) that I don't have on my stock 10.4 system.

What I can do is start in single user mode. If I knew a correct command line to enter in Single User I could correct the resolution at least enough to finish booting and then get to the GUI interface again.

Please help, the machine is unusable at this point.

lb

Damien
10-01-2007, 04:52 PM
Do you have another screen you can connect? That would be the easiest way.

Does your screen have an Autosync button?

unclemac
10-01-2007, 05:20 PM
As I recall, a PRAM reset will return screen resolutions to the factory default....

Ah yes, here we are (http://docs.info.apple.com/article.html?artnum=86194). Looks like that should do it.

levelbest
10-01-2007, 05:29 PM
http://www.westwind.com/reference/OS-X/commandline/single-user.html

This page looks like it has good information. I will be happy to find an easier softer way, of course.

I have an old 14" monitor and it did boot into that just fine. I changed the resolution to where it was on the sgi and then shut it down. I reattached my SGI 21" monitor and it still will not boot an image. Says it is still at 85 Mhz and refuses to work.

I haven't thought of Pram Zapping since the old days. How does that work on 10.4.9? Holding down the "P" and R" keys while booting with a modifier key of I recall (Option?)

I did a fsck -yf and I used Applejack already.

Is it possible I need to go in with the working monitor and rip out the .plist file somewhere? Is it seeing the SGI somehow differently? Using the same machine on each monitor but changing one does not appear to have affected using the other.


To zap the PRAM:

Press and hold the COMMAND + OPTION + P + R keys during startup
Continue holding down all four keys until you hear your Mac reboot four times
Release COMMAND + OPTION + P + R

I just tried this, didnt make any difference.

unclemac
10-01-2007, 05:36 PM
Should be just fine. Mostly tied to hardware, so although there are some small differences with OS X, it is mostly the same, and a safe thing to do:

Shut down the computer.
Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
Turn on the computer.
Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
Hold the keys down until the computer restarts and you hear the startup sound for the second time.
Release the keys.

levelbest
10-01-2007, 06:30 PM
No. This didn't fix the problem. I have it rebooted with the smaller monitor and I would like to learn which plist file to rip out?

Or, go after it in single user mode.


ADDED --->
I just ran the firmware update mode to zap the NVRAM. That didn't do it either.

HELP!

rwm
10-01-2007, 06:55 PM
Single User...
http://docs.info.apple.com/article.html?artnum=106388

Anything like a (reset) on the monitor?

levelbest
10-01-2007, 06:57 PM
Yes, outlinded pretty well on this page:


http://www.westwind.com/reference/OS-X/commandline/single-user.html

Nicolas
10-01-2007, 07:07 PM
No. This didn't fix the problem. I have it rebooted with the smaller monitor and I would like to learn which plist file to rip out?

Or, go after it in single user mode.


ADDED --->
I just ran the firmware update mode to zap the NVRAM. That didn't do it either.

HELP!

You mean you went in OpenFW by holding down Apple+ALT+F+O
then you was reseting everything by doing this:

reset-nvram
set-defaults
reset-all

Right? or Wrong?

This should fix the issue if the monitor is DDC capable and is allright.

Regards

Nicolas

levelbest
10-01-2007, 07:12 PM
You mean you went in OpenFW by holding down Apple+ALT+F+O
then you was reseting everything by doing this:

reset-nvram
set-defaults
reset-all

Correct. Although I didnt see the middle line mentioned in my example so I didnt do that one, "set-defaults"

I will do it again with that line, just in case it help,

unclemac
10-01-2007, 07:24 PM
Huh....thought the PRAM reset would have done it. OF reset should do it. If not........something esle wrong? Seperate video issue? Did you see the screen to do the OF reset, of did you do it blind?

levelbest
10-01-2007, 09:22 PM
It shows a grey screen with the silhouette apple logo monochrome and the little spinner (not the color beach ball - the spinner) when it first starts up.

It works in single user mode fine. Shows a black screen with the appropriate command interface. Which is why I was asking f anyone knows how to change the res in singe user mode.

It works in o-f mode fine. I followed the instructions in this thread, as well as similar instructions earlier. But that did not affect the monitor.

When it has to turn to a OS X blue screen background, the screen defaults to black

IT shows the same warning window that it shows when no input has been detected, except it changes to the following:, small rectangle, in the center of the screen.



INFORMATION

Monitor is working
input 1:128.4KHZ/85 Hz

Out of scan range

Change signal timing

White
Red
Green
Blue



The odd thing is that it works on the little 14" monitor. I can change res on that monitor but reattaching the 21 SGI and rebooting doesn't change the SGI.

Well, the script on single user boot does show larger so it apparently is being affected, but it is still not going into GUI.

levelbest
10-02-2007, 08:41 AM
After a nights rest, I am still at it. I can't get a screen on the SGI after the initial grey apple logo screen or the default black with small warning screen in the middle so the controls don't seem to be of much use to me at this point. Really frustrating as I finally got the added ram I was lacking to run Lightroom and LightZone at the same time and now I am trying to get some overdue work done.

Considering all that has been suggested so far on this thread, which I have now tried and I sincerely appreciate, I think I need to learn how to either find the plist file that references the monitor settings and rip that out and let the system rebuild one again from scratch, or,

Learn to reference the monitor through single user mode, booting up with no gui interface (gulp). At this point, that would be all right with me as I am tired of not knowing how to do what I know this system is capable of doing.

In the mean time I have my old MDD SP G4 laying about with a different graphics card. I plan to boot from that one just to see what the monitor does with it.

I have also been casting about for additional information on the SGI in case it has some odd reset feature that I may need to know about. No luck so far though. This model has two VGA inputs and I tried switching the channels just in case, no joy though.

lb

kaye
10-02-2007, 09:08 AM
lb,
Long time ago had a Sony CRT. It had a memory of a certain number of resolutions, don't remember how many. If the memory got scrambled or I tried another resolution that would not work, there was a reset button that would set everything including resolutions back to default. Had to hold the button in for at least 2sec as I recall. k

levelbest
10-02-2007, 09:25 AM
Thanks, I will look for a manual for the monitor and try that. I was holding each button for the standard 2 to 5 second time and I was getting something (screen changes). No fix though.

I just discovered a link where the plist fie was mentioned and also that holding the shift key down during startup tells the monitor to reset. Will write again in an hour or so after trying the next things.

Thanks.


http://www.macosxhints.com/article.php?story=2001100114532165

... i could no longer use OS X, because it kept booting the computer up in an invalid range and i couldn't see the OS to change the resolution. The mac has handled this kind of thing far more elegantly than Windows for at least a decade - to revert to this kind of unintuitive behavior is just inexcusable.

in any case, i could not do a thing to make this work. zapping the PRAM no longer resets the monitor values to a default like 640x480, and disconnecting the monitor, shutting down, booting, shutting down, plugging in the monitor and booting didn't do it either. After asking around on another BBS, i was able to get the system back. deleting the file:

/Library/Preferences/com.apple.windowserver.plist

while in 9.2 and rebooting into X worked fine. It inherited the settings from 9.2, and i'm now working from 10.1 again.

-perry

December 20 2001 Update: An alternative method of solving this problem is to restart with the shift key down during a reboot - this seems to now indicate to OS X "reset the monitor at startup" instead of "disable extensions". This solution courtesy of this thread on the MacNN forums.

levelbest
10-02-2007, 09:55 AM
UPDATE. - Problem Solved.

The tip I found to start up holding the shift key down is what finally solved the problem. Safe Boot mode is what Apple calls it (said so on the log in screen).

I recommend this tip for others who accidently get in the same position. Zapping Pram, changing NVRAM, Using another monitor, none of those things worked. Telling the machine to ignore the custom settings for the monitor by booting while holding the shift key, thank God for that.

It looks like I was on the right track to rip out the preference file, it was my next step. I didn't have to but here it is, according to the same tip:

/Library/Preferences/com.apple.windowserver.plist

I never learned how to do this in single user mode, but, I am glad it is working again.

Now, back to work. Much thanks. lb-

rwm
10-02-2007, 11:52 AM
I can't believe that none of us mentioned that. I think it crossed my mind but figured we were dealing with something tougher. :o

unclemac
10-02-2007, 12:36 PM
Good to know. Learn something new every day.

Didn't know that Safe Boot set defaults, and I would have bet PRAM and/or OF reset would have.......especially since Apple says it would.:rolleyes:

levelbest
10-02-2007, 12:52 PM
Yep, and thanks again for the help. I am sure I am not the only one that experiences lone wolf Mac syndrome. Walk in most PC supply driven chains, Best Buy, Circuit City, to look at (anything, graphics cards you know you have to flash, pioneer burners that are listed as Windows only, etc) and get either a blank response from the clerk or a for sure statement like, "that is impossible" statement.

Really, I always appreciate the conversations and the help here.

So happy I changed my avatar to reflect a thread when I got my 1.25 DP and my 77 Gold wing on the same shoe string. It seems only fair ... ;-)

lb