It sounds like your monitor was workinf fine before you upgraded to OS X 10.9 but now is not recognized. I recommend the troubleshooting steps from this article named:
Apple computers: Troubleshooting issues with video on internal or external displays
No video or no signal, image distortion, "snow," or flickering
When using an external display be sure to check the following:
- If you're using an Apple notebook, confirm the AC power cable or adapter is securely connected to the computer and the cable providing power to the display is also secure. It is always good to have your notebook connected to AC power when an external display is in use.
- Confirm display adapters are fully seated in their respective connections and that they are supported models and for the computer and display. Refer to these articles to assist you with adapter compatibility and further configuration information:
- Remove all display cable extenders, KVM switches, or other like devices and retest to determine if the issue is resolved.
- Try unplugging the video adapter or cable and then plug it back in.
- If more than one video adapter is in use (or "daisy-chained"), troubleshoot by using only one adapter.
- Example: A mini DisplayPort to DVI adapter connected to a DVI to HDMI adapter is an unsupported configuration because there is a series of adapters in use.
- If available, try using a different display and or adapter (or use a different connector by using DVI instead of VGA, for instance).
Reset the system
You can reset the Mac's parameter RAM and SMC.Reset the resolutionStart by resetting the Mac's parameter RAM. If the display does not come up, was previously set to an unsupported resolution, and still results in no video:
- Start up in Safe Mode.
- From the Apple () menu, choose System Preferences.
- Choose Displays from the View menu to open the preferences pane.
- Select any resolution and refresh rate that your display supports.
- Restart your computer.
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All the best,
Did you try "Detect Displays" (hidden in the Diplsay Preferecne Pane). System Preferences > Displays > then hold down the 'Option' button and note the 'Detect Displays' button that appears in the botton right. Click it. Might not work - but worht a try.
I get this problem on my late 2009 macbook pro with an external dell monitor connected with a dvi adapter...
Sometimes to get it to work when it won't see the 2nd monitor,
- I unplug the DVI cable then shut down the laptop
- start it keeping the 2nd monitor unplugged,
- once I am logged in, I plug in the 2nd monitor DVI adaptor and usually after a few plug and unplug attempts; the second monitor usually gets recognized and starts working again
this supremely frustrating and time consuming work around has been the only way i have got my 2nd monitor to work since the latest mavericks update....
quick ammendment, unplug the dvi cable and then unplug the monitor from the dvi cable... then shut it down...
once you are logged in and everything is loaded, then plug in the dvi cable, and then connect the monito cable to the dvi cable...
following this process is the only way i can get it to recognize my dvi cable.
display mirroring is still not showing up in my menu bar, but everything else is g2g at least...
Sterling, I have had this exact problem on several versions of OSX. It was always quite easy to fix by click the "Detect Displays" button in display preferences. However, this is gone in 10.9. Can I still run this command via terminal, do you know why it was removed or what it's equivalent is? It was such a simple fix, and I am frustrated to see it removed.
Actually I just found this article about the detect displays command. Works great and is very easy! I am using DVI to Thunderbolt also with an older Acer monitor.
Hey anyone who has the "diamond monitor adapter" from displaylink.com or any other adapter from a company were you had to download some software in order to use it. I would highly suggest you checking out your product's company site and checking for updates. They might have updates that help with Mavericks. One failed attempt after another from dusk till dawn I'd been trying to solve the problem. But one final idea I had was to check the site and hope they had some sort of update that fix this problem. I have the "diamond monitor adapter" and I have a thunderbolt adapter for another monitor(The thunderbolt was detected from the start of me installing mavericks). The diamond monitor adapter wouldn't be detected until I check out the site and downloaded an update. If you have this adapter and have this problem just click the link and downlaod the update. - http://www.displaylink.com/support/sla.php?fileid=110
Your mac should restart on its own then your mac and your monitor connected to thunderbolt's screen(Assuming you have dual monitors) should be active at the same time. Then once you make it to your desktop go to System Preference > Display and then it should detect the 2nd monitor instantly, but if not just go to "Gather windows" change it to Detect Displays using option(alt) and then it will instantly detect that 2nd monitor and you'll be so happy you want to help those who also had this problem like I'm doing now.
I really hope this helps because I couldn't find any other way.
Thanks KillDash9. After hours of searching for a solution your suggestion worked in 3 seconds. It is this kind to foolish OS design that will send me running back to Windows. Why is making the "Detect display" button invisible regarded as good UI design my Apple? Amazing lack of usability for such a simple need. Thanks again.