[zgall1]

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 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.

[badsey]

from iMac help:

I changed my display's resolution and now there's no picture
You may have selected an unsupported screen resolution. To resolve the problem, you need to restart your computer in "Safe Mode" and then choose another resolution.

To start up your computer in Safe Mode and choose a different resolution:
Shut down your computer by holding down the power button.
Restart your computer, and immediately after you hear the startup tone, press and hold the Shift key. (Don't press the Shift key before you hear the startup tone.) Release the Shift key when you see the progress indicator below the gray Apple icon. Startup may take a bit longer than usual.
Your displays should begin working correctly.

Choose System Preferences from the Apple menu.
Click the Displays preference pane.
Select a resolution and refresh rate that is supported by the display.
Restart your computer.

[zgall1]

This suggestion does not work.

[ghporter]

Your response is not illuminating. WHAT doesn't work - which step? Specifics are important.

[zgall1]

I can't tell if it is restarting in safe mode because the screen remains black. My response is only one line since I specifically stated in my original question that starting in safe mode does not work.

[ghporter]

It looked like you had said that you had something on the screen in safe mode, thus my question. Are you sure your monitor is still working properly? Some (older) CRTs can actually be damaged by the wrong input signals, and more recent ones have a tendency to be picky about turning back on after a "bad" input event.

What kind of monitor and what computer are you using?

[PCP210USER]

zgall1, I have had some problems with my monitor not seeing my mac's signal. I have no idea why it happens, especially because it's intermittent. In my case, it may be because I have a cheapo monitor attached to my G4. Anyway, I don't know if this will help you, but it may be worth a try. When this problem happens to me, I have to plug a different monitor into my mac. The 'new' monitor is seen and displays the computer's signal. I can then go back to my 'old' monitor and view the computer.

In addition, some weirdnesses--generally speaking--can be resolved by re-seating the graphics card.

[analogika]

In some cases, booting while holding down the "M" key will reset the monitor settings.

[seanc]

Or resetting the PRAM/PMU may do it.

[veri]

Originally Posted by ghporter 

What kind of monitor and what computer are you using?

I have the same problem. I have a PPC Mini Mac connected to my Panasonic plasma TV (TH-42PV60E). It used to work just fine, but after tweaking the monitor settings, I can't make it work anymore. It still works perfectly on my spare monitor (LG 15" LCD monitor).

The Panasonic has both a VGA and HDMI input. I've tried both. When I boot the Mac connected to the VGA input, it displays an out of sync image. On the HDMI input it just goes black.

The display turns black/out of sync after displaying the "Starting OSX" screen for a few seconds.

I've tried all the tips I've found, but nothing seems to work. Booting into safe mode doesn't help either. It still changes to an unsupported screen resolution on startup.

If I boot with my spare monitor attached, I can change the screen resolution and refresh rate, but I've still not been able to make it work with the Panasonic.

Is there any way to permanently erase all monitor settings, and have the OS boot in it's default setup?