AAM: Resolution Troubles on HDTV using Mac

Hi folks,

At the time of writing this week, we’ve been lumbered with a question that is causing quite a discussion on the Apple Matters forums. User BigMac has recently hooked up his G4 Dual, running Panther, to a 21” HD flat screen TV via a VGA-to-VGA cable. Unfortunately for him, he’s accidentally set the screen resolution too high for the TV, forcing a horrible looking message on the screen along the lines of “Incompatible Format”. A few suggestions from regular forum members have so far proved unsuccessful, but the attempts made could possibly help out others in this situation. If you fancy helping out, feel free to drop by the thread Resetting Screen Resolution At Startup and leave a message. The problem is still unsolved and you could get a mention in next weeks post if you manage to find success for BigMac. In the mean time, here are the answers some users have submitted below:

Question Of The Week

Resetting Screen Resolution At Startup

Question by: BigMac

I have a G4 Dual 450 Running Panther that I hooked up to a small 21” HD Flat Screen TV through VGA to VGA cable. It worked fine but then I went ahead and started fiddling with the screen resolution settings and set it to something the TV cant handle. I got a screen on the tv saying “uncompatible format” but I can’t figure out how to switch it back without plugging it into another monitor (which I don’t have). I tried restarting and that didn’t work.

I just installed the OS so I have nothing on it yet. Is there a keystroke to reset back to factory settings?

Answer by: Buzz Bumble

I’m not sure what Mac OS X does, but in the good ol’ days of the proper Mac OS when switching the screen resolution the Control Panel used to pause in the new setting with an OK / Cancel window and if you didn’t reply within a few seconds (or clicked Cancel) it simply switched back to the original setting.

If Mac OS X is the same and you’ve clicked OK or some sort of equivalent, then you could be stuck.

Simply re-booting won’t fix it since the setting is now saved. A couple of things to try:

- resetting the PRAM
- boot from the Mac OS X install CD / DVD (and probably re-install the OS)

Depending on the setting you used, finding a monitor that can handle it might be difficult.

Answer by: Frozencold

Okay you have to reset the PRAM by; pressing Command-Option-P-R at startup until you hear the startup chime twice - that should reset the screen resolution. But to what it resets to, I don’t know.

Feedback from BigMac

Ok. I reset the PRAM and that did not work. I then located a monitor and was able to change the resolution mode on the computer, save it and then switch the cables to the TV. The screen then worked, but when I restarted the computer it reverted back to “Cannot display this video mode”
Is this a TV issue perhaps? Or is this a computer issue?

Answer by: Frozencold

I think it may be a TV issue, keep the Mac connected to the monitor and restart, so you can see if the resolution reset itself. The pram method might not have worked because whatever resolution it reset to was too high. BTW: What resolution, did you set the Mac to, for the TV?

View forum Resetting Screen Resolution At Startup and add your own answers.

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