How to mirror desktop

The primary display on my iMac 17in late-2006 intel has failed. I can't see the primary display and the display manager is set to show extended desktop. All I can see on the secondary display is a picture. Is there a way of forcing a mirrored desktop if you can't see the primary desktop? Alternatively, is there a way of opening up the system preference windows on the secondary display when you can see to drag there? Thanks, Blair

You could try randomly dragging the mouse from one screen to the other to try to nab it.

Reboot the computer, keep the primary 17" MBP top lid closed. It should boot to the secondary display allowing you to make changes. You will need an external keyboard and mouse to make it work.

AppleCider: Thought of that. You wouldn't believe how hard it is to do just that but I can keep trying.

chscag: Thanks, but I have an iMac not a powerbook.

Sorry about that. No way to close the lid on an iMac is there?

Can you get access to another Mac? If you can, use Target Disk mode to boot your Mac and then set the display options in System Preferences. You'll need a FW connection on both Macs. See this Apple KB article: LINK

chscag: Thanks for this. I do have a G4 desktop with a firewire port and a cable somewhere so can try this. However, I'm murky on what to do if I can get a connection. The iMac will be the target and the G4 the host so system preferences will be for the G4 not the iMac. Presumably there is a configuration file on the iMac that can be edited or even deleted that will force the iMac to use a mirrored desktop when it is disconnected and rebooted. Can you point me to help on that? I've even thought of opening up the iMac and physically disconnecting the defective display. Perhaps the iMac is smart enough to then switch to the secondary dispaly - sort of like keeping the lid closed? Thanks, Blair

Found this link related to problems with the radeon chipset in the iMac.https://discussions.apple.com/thread/2570597?start=0&tstart=0

It contains a link to a clever hardware fix that involves baking the logic board to reform bad solder joints. Worth a try if the alternative is an unusable machine.