Tidbit for Windows Users: Press Windows Key and P for easy display switching.
With the advent of OS/X Mountain Lion, some simple things became complex things, for now :-)
Here are some things to do. If all else fails:
power down the Mac,
power down the projector.
Then disconnect the cable joining the two devices (as sometimes they really aren't off).
Then (re)connect the Mac to the projector .
This way the projector will start presenting, at least, analog voltages for very old VGA devices. Most modern devices VGA devices and anything newer will start sending out joyous, digital "I can do this" signals down the wire toward the computer.
Turn on the projector FIRST!
Then turn on the Mac. The computer can now accept and digest the projector's digital messages and do a "best guess " of what to do with the attached device.
If nothing appears, try Option and the Brightness adjustment keys
As always, the Option (alt) key is your path to hidden Mac functionality :-)
Also there are free non-Apple apps to make this all EASY!
See also: Apple's guide for video problems, Apple computers: Troubleshooting issues with video on internal or external displays.
Old Mac hands: Note that the first step here, checking for Software Updates, now uses the Mac App Store as of Mountain Lion (OS/X version 10.8)
Apple's reasoning is good for the long haul. If the problem is something already fixed by a software update, avoid mucking around trying to fix it other ways. Most times, though, the software on the Mac is just fine.
OPEN DISPLAY PREFERENCES FROM THE KEYBOARD:
Best Keyboard based tip for displays:
Rather than taking the long route through the System Preferences, hold the option (alt) key on your keyboard and press one of the brightness adjustment keys to open the Display preferences pane straightaway.
From: 3 Ways To Manage Display Settings In Mac OS X Mountain Lion
http://www.makeuseof.com/tag/3-ways-manage-display-settings-mountain-lion/
Pro: Works on any OS/X Mountain Lion system.
Con: Remembering the magic keys to press :-)
Apple's standard method for setting displays is found at http://support.apple.com/kb/HT5369 entitled:
Here again, the Option key is your friend:
If the detect displays option is not available, hold down the Option key while you are in the Display pane.
Pro: Useful option
Con: Was easily found before, now is hidden by default.
People really are not fond of tromping to the System Preferences as in days of yore :-), or remembering to press Option.
Nice, easy solutions are:
A Free App called Display Menu By Milch im Gemüsefach on the Mac App Store.
A Free App called QuickRes found at http://www.quickresapp.com/
These seem to be good solutions for those pining for missing Display Preference Menu :-)
The recent change seems to have been made as the support for AirPlay (wireless Video and Audio streaming via Apple TV) was refined.
(Scroll up or down for more information)
There are a number of types of connections around for devices displaying images (which may do other things too).
DVI - Digital Visual Interface which is a step up for computers from VGA but is now being phased out.
HDMI -High-Definition Multimedia Interface : your new tablet computer or video camera may use this.
DisplayPort - Apple has a nice page (with pictures) explaining the many subtle differences between connectors
Apple Mini DisplayPort adapters: Frequently asked questions (FAQ)
Thunderbolt - This is the mini-DisplayPort combined with a digital interconnect technology called PCI Express.
In a world where "content is king", copy protection lurks down below with High-bandwidth Digital Content Protection:
The system is meant to stop HDCP-encrypted content from being played on unauthorized devices or devices which have been modified to copy HDCP content.[2][3] Before sending data, a transmitting device checks that the receiver is authorized to receive it. If so, the transmitter encrypts the data to prevent eavesdropping as it flows to the receiver.
So your digital content is travelling through something descended from a WWII System that allowed Churchill and Roosevelt to communicate securely. Just to go from one device to another.
Why? Sadly, a digital pirate, having wrenched the raw bits of the work free of the copy-protection, can easily copy, play or modify the work. Perfect copy after perfect, on and on...
Beyond the image headed from your computer to the device, there are other messages going back and forth between your display/projector/TV/holographic imager :-)
On modern VGA devices, we have Display Data Channel. Happily, this stops us literally blowing up displays by specifying the wrong settings in software! The configurations are automatically provided using the Extended display identification data or EDID.
What sort of stuff is in that EDID?
We can ask the Mac questions about the external monitor with a UNIX command like:
new-host-2:~ me$ ioreg -lw0 |grep -6 --color -i edid
which produces the not very enlightening:
"IODisplayEDID" = <00ffffffffffff004c2d12064451325a0e150103803c22782aeed1a555489b261250542308008100814081809500a940b30001010101023a801871382d40582c45005c562100001e000000fd00383c1e5111000a202020202020000000fc0053796e634d61737465720a2020000000ff0048434b423430303139390a2020004c>
We can hunt for human-readable text in that via:
new-host-2:~ me$ ioreg -lw0 | grep IODisplayEDID | sed "/[^<]*</s///" | xxd -p -r | strings
DQ2Z
?<"x*
q8-@X,E
SyncMaster
HCKB400199
new-host-2:~ me$
Hmm. What is SyncMaster? Well, that's the type of display I have connected!
Here are some pictures SAMSUNG SYNCMASTER monitor
For older versions of OS/X check out the page:
This covers topics including: Video mirroring, Extended desktop and Closed clamshell (laptop as a desktop use).
If you, like me, hear annoying high pitched noises around CRT-based TV's and monitors, here is the reason why.
When they tested our hearing in elementary school, the audiologist seemed very surprised I could hear the highest range the testing machine could generate.
November 19, 2012