Changed iMac G3 OS Resolution too high and now the screen is blank?

[TakaEdakumi]

To be fair, this actually happened many years ago now, and my brother (the one who did it) has tried many things to get it visible again but to no avail. Most notably we tried holding shift down at startup and also using a startup disc, but neither of them caused any change.

The computer seems to be running perfectly fine other than lack of visibility, but by now we couldn’t possibly reset the resolution by memory. Resetting it completely is out of the question, as we are trying to access nostalgic game data specifically.

Anyone have ideas or possible solutions?

 

[TheShortTimer]

Resetting it completely is out of the question, as we are trying to access nostalgic game data specifically.

Anyone have ideas or possible solutions?

Does your iMac G3 possess FireWire ports and do you have access to another Mac that also has FireWire ports? If so, connect them and start up the iMac with T held down to activate Target Disk Mode, copy over the game data and then restore the OS from scratch. Once it's reinstalled, you can copy the game data back onto the iMac and continue where you left off.

 

[chscag]

Usually when you subject a CRT to a higher than spec refresh rate, the screen will go blank but restarting usually brings it back.

Try setting the refresh to 75 Hz. That should equal a resolution of 1024 x 768.

I have no idea how you do that on an iMac G3. I'll let you figure that out.

 

[eyoungren]

Reset PRAM. CMD+OPTN+P+R when you start the Mac up. Keep holding until the Mac has chimed 2 or 3 times, not including the first one when you turn it on.

PRAM restores things like sound levels and video resolution to defaults.

 

[DeltaMac]

Do an Open-Firmware reset.

Boot holding Option-Apple(Command)-o-f
(that's the letter o, not the number 0)

You SHOULD boot to a text screen, showing which model Mac you are booting (like iMac,1 or PowerMac2,2) and a line or two of text.
Even if you see nothing on the screen, try typing the following (no spaces), one command at a time, pressing enter after each command.

reset-nvram
set-defaults
reset-all

Assuming that you tried the correct Option-Apple-o-f, you don't need to see anything on the screen, just try the commands, followed by Return. You should get an "OK" after each command. Don't worry about that if you can't see anything yet, just type the commands.
At the last reset-all, then press return, you should get a full restart on your iMac (with the boot chime sound, AND that is a full reset of the hardware. If you don't get any video, then it's not software - you have a video failure, and you will need to retrieve your important files from the hard drive. It's pretty easy with Firewire, but you need an iMac WITH firewire ports, and you need a second Mac, also with firewire ports. If your iMac G3 is older (with a CD drive that has a tray, not a slot in the front) then you will need to remove the hard drive to get the data.

 

[TakaEdakumi]

Do an Open-Firmware reset.

Boot holding Option-Apple(Command)-o-f
(that's the letter o, not the number 0)

You SHOULD boot to a text screen, showing which model Mac you are booting (like iMac,1 or PowerMac2,2) and a line or two of text.
Even if you see nothing on the screen, try typing the following (no spaces), one command at a time, pressing enter after each command.

reset-nvram
set-defaults
reset-all

Assuming that you tried the correct Option-Apple-o-f, you don't need to see anything on the screen, just try the commands, followed by Return. You should get an "OK" after each command. Don't worry about that if you can't see anything yet, just type the commands.
At the last reset-all, then press return, you should get a full restart on your iMac (with the boot chime sound, AND that is a full reset of the hardware. If you don't get any video, then it's not software - you have a video failure, and you will need to retrieve your important files from the hard drive. It's pretty easy with Firewire, but you need an iMac WITH firewire ports, and you need a second Mac, also with firewire ports. If your iMac G3 is older (with a CD drive that has a tray, not a slot in the front) then you will need to remove the hard drive to get the data.

We tried this as you described, but nothing seems to happen? I don’t know if we’re missing some step but we attempted it a few times and it doesn’t restart itself at any point.

We tested the keyboard on another working one and the keys are functioning properly, and the computer does make the initial chime noise so the sound isn’t broken either.

Unfortunately, it is indeed the version with the disc tray, but I am not the most tech savvy, so I’m not sure how to go about removing/getting anything off the hard drive itself?

 

[DeltaMac]

Is your keyboard Apple-branded? Other brands, especially generic brands that are sold as Windows keyboards SHOULD work, but may not accept the boot commands. (Try a different keyboard) If you are using an Apple-brand keyboard, can you get the boot chime when you try a PRAM/NVRAM reset? That's booting while holding Option-Command-P-R.
Your SHOULD hear the boot chime sound. Keep holding the same 4 keys until you hear the boot chime 2 more times, continue holding until the boot chime again sounds, immediately moving to Option-Command-o-f.
(If nothing appears on the screen, then just hold the keys for 10 seconds, before releasing)
If you do get any response from the screen. Hold THOSE keys until you see the text screen, then try the commands that I listed, one at a time, and in the order I posted, pressing enter after each command. If you still don't see anything on the screen, just type each command, followed by Enter.
The ONLY time with those commands that you should get a restart (with the chime sound), is after the reset-all command. The other two commands will only result in "OK", no reboot, and no sound of any type. Again, if you see nothing, type the command (don't forget the (-) between reset and all)