External Monitor in Target Display Mode Won't Wake Up

I'm using 2 imac 27' and one is simply used as an external display. When I wake up the computer from sleep, it works on the main monitor, however the external display still has a black screen. I have to unplug the external monitor to get it to wake up. Is there anyway to fix this? I tried unplugging thunderbolt and replugging it in which worked the first time, but same issue again not waking up.

Same issue here, I'm using a macbook pro retina and connecting to a 27 inch imac via thunderbolt and target display mode.
I also have a 27 inch thunderbolt display hooked up via tbolt cable as well.
Whenever the displays goto sleep, the iMac does not wake up with the other screens. My setup knows the iMac is part of the displays, it doesn't act like there are only 2 screens available.
If I press the target display mode shortcut (command + f2) then the imac screen turns on, but now its left target display mode (so it clearly is in target display mode, but does not receive the command to turn on display or ignores it). Hitting hte shortcut again now switches back.
I have not tried just the mbpr + imac as target display mode, but based on your post it still wouldn't wake up if it was the only machine connected.
I've found that when I come back to my computer, i just hit command +f2 on the imac, which wakes it up and jumps to its screen, t hen i hit command +f2 again, and now I wake the mbpr from sleep so it doesn't have to go from 2 screens to 3 screens.

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I have a late 2010 MB Air (mini display port) and a new 2013 iMac (thunderbolt) which I would love to use as an external display. I suspect that target display mode won't work.Any ideas for how to achieve this?

According to the TDM support page, this isn't possible. I tried it with a Mnidisplay port to minidisplay port cable without success. Its a shame that thunderbolt doesn't appear to be backwards compable as I could have achieved this with an older iMac.
Cheers

You are correct....it will not work. Please carefully read Apple's Target Display Mode: Frequently Asked Questions (FAQ)

Using iMac (Target Display Mode) as an External Display for MacBook Air

I have a Mid 2010 iMac with a 2 thunderbolt ports. I now have a brand new MacBook Air (2012 Core i5 1.8GHz with 8GB RAM) with a thunderbolt port. I have a Belkin Mini Displayport Cable to connect the two. I want to use the iMac as an external monitor for the MacBook Air. I cannot seem to get this to work. Can I do this? Do I have the right cable?

You can do it but you need a thunderbolt cable to connect the two. Then just hit CMD F2 on the iMac and it will enter Target Display Mode.

Two i3 iMacs won't work in Target Display Mode

I do have Belkin Mini DP to Mini DP cable. Command + F2 doesn't help either. Please help

24. Can I use Target Display Mode or Target Disk Mode with Boot Camp and Windows 7 or 8 using a Thunderbolt-capable iMac?
No. Target Display Mode and Target Disk mode are not supported using Boot Camp and Windows 7 on a Thunderbolt-capable iMac.
http://support.apple.com/kb/HT5219?viewlocale=en_US#17

How do I get Windows 7 to display in Target Display Mode on IMac

I am increasingly frustrated by my inbability to get my Mac Mini running Windows 7 to display on my late 2013 27" IMac using Target Display mode.
My setup:
1. IMac 27" Late 2013 running OSX 10.9.2 with all the latest drivers as of Mar 7, 2014.
2. Mac Mini Server Mid 2011 running Windows 7 SP1, 64bit, all the latest Windows drivers as of 3/7/14, using the latest BootCamp Drivers for this machine, ver 5.1 downloaded 3/5/14 to this machine using Boot Camp utilities in its OSX mode.
3. Connected via Apple Thunderbolt cable.
My process is as follows:
a. Turn on the IMac, boot up in the normal manner, preparing it to run in Target Disk Mode in OSX.
b. Turn on the MacMini boot up via BootCamp, in the normal manner in to Windows 7.
c. When Both machines are on and connected via their Thunderbolt ports, I enter cmd-F2 on the IMac keyboard to enter Target Disk Mode.
Nothing happens.
I use this IMac to display my MacBook Pro in OSX, so I know it is working, but I can't see where the problem is.
I have reviewed all of the Apple support information and followed it explicitly, to no avail.
When I have called the Apple support team, I get little help, they assert that they can't troubleshoot because it is not all Apple hardware/software (everything including the Thunderbolt cable is Apple except for the Windows OS)
Any suggestions will be welcome...
Thanks!

I have finally achieved some clarity on how Target Display Mode works, or rather doesn't work.
And I have been mistaken in some of my prior comments.
Target Display Mode is a function of the host machine, at this point only the IMacs. And it is only available when the host machine is running OSX.
But the most recent Thunderbolt versions of the IMac have been significantly dumbed down in this functionality.
The prior generation of IMacs whose video was supported through the Mini Display Port supported almost any input from a Mini Display Port compliant Computer through the use of various mechanical adapters, and certainly from any Mac Hardware or software combination. It was a very versatile setup, and the IMac in this manner could serve as an absoloutely beautiful monitor for a wide variety of hardware/software combinations.
When the current version of the IMac was deployed using the Thunderbolt ports for input for external video, we apparently left a world of standards based video input and entered the world of Apple proprietary video.
The current model of IMacs with thunderbolt video have a very limited functionality in Target Display Mode compared to those of us who have used it previously. and it only functions when the client machine is running OSX.
No other video input from any source will display.
I am not quite clear on the reasons one would want to display OSX on an OSX native machine, but you can do it. I guess MacBook Pro or Air running OSX will now display on the IMac if that is your need.
Likely the most likely need for Target Display Mode for the rest of us is to run Windows on an external machine and display the video on the IMac, as we have been able to do with the prior generations of IMacs for several years now.
Apple has been unwilling to distribute the technical specifications of its video input requirements in Target Display Mode, (other than to assert it requires OSX), and these technical specifications appear to be proprietary.
I have personally unsuccessfully tried to display the output from both Windows 7 and a Windows 8 machines running from a Windows thunderbolt port into a thunderbolt port on a current model IMac using Target Display Mode.
Unfortunately, there are still a few applications that won't work in Mac world and require a native Windows machine. My current need is to run Dragon Naturally Speaking via Citrix to a remote Citrix server and a Windows app. Parallels and VMWare Fusion do not work, nor does the OSX version of Dragon Dictate function via Citrix. So I am stuck.
I hope that Apple, so long a leader in technology, will restore the functionality it abandoned when it embraced thunderbolt as its only video iniput in Target Display Mode.
Thanks!

Mid 2010 27" IMac Target Display Mode has stopped working

I have a 27" mid 2010 IMac, NOT the thunderbolt version, and have been using it in target display mode for my Mac Pro and 2010 Mac Mini with no problems. I have used the Belkin cables, and routinely would switch between internal and external machines using Command-F2. Worked like a champ for about 7 months.
Today, with no obvious change, I cannot get the IMac to enter TDM. This is true whether I use the Mac Mini or the Mac Pro, and is true using either of two Belkin Cables.
I reset the PRAM and NVRAM on the IMac, but this made no difference. I changed keyboards from my Bluetooth IMac keyboard to an Apple USB keyboard. Again, no improvement. I have rebooted the machine without benefit. The IMac seems to function just fine in every other respect.
Since I have no other monitor that supports the mini DisplayPort on the two other machines, I am dead in the water at this point.
The machine is a mid 2010 27" IMac, OSX 10.6.7, 2.93Ghz I7 CPU, 16 Gb RAM, 480Gb SSD and has worked well for quite a few months.
Any help will be appreciated.

When the display only shows the background, it's working in extended desktop mode. That's a logical extension of your desktop to the right of the MBP. Drag an application off the MBP to the right and it will appear on the iMac. When you close the lid of your MBP the iMac becomes the primary monitor in Clamshell mode.
If you want to mirror the MBP to the iMac then press CMD F1, press again for extended desktop mode. These settings are in System Preferences > Display > Arrangement tab.
When the iMac is in Target display mode, you don't use the keyboard on the iMac. Use the keyboard on the MBPro.

Blurry fonts in iMac in Target Display Mode

When I connect Macbook Pro retina with iMac using Thunderbolt to Thunderbolt cable, and use iMac in Target Display Mode the text and fonts are really blurry.
It is the same text in Macbook:
Text in iMac:
The resolution of iMac display is "Best for display", however, I have tried to change it without any success.
Does anyone has similar problem or anyone knows how to fix it? Thanks in advance!

I have found an interesting regularity. If I open window (let's say PDF file) in Macbook Pro and drag it to iMac, then everything is okey. Unless I resize it. Once I resize it, it becomes blurry/smooth again.
Why had this problem and how to fix it?
Changing the resolution in Macbook Pro can help, but 1) I need to change the resolution in Macbook every time when I connect external monitor 2) I cannot resize windows in iMac 3) if I change resolution in Macbook Pro items become really small, so it is hard to see something.
Please help!
OS: OS X Yosemite 10.10
Macbook: MacBook Pro (Retina, late 2013)

Audio on iMac in target display mode.

Here's my problem:
I have a macbook pro with retina display that is hooked up to an imac via thunderbolt. The imac is in target display mode so that I can use it as a second monitor. I have some external speakers attached to the imac which I use when I'm using the imac by itself. I'm trying to make it so that I can use these speakers when in target display mode.
When in system preferences I can set the sound output to the imac but the audio plays through the internal speakers instead of the external. Anyone know a way to make this work?
Thanks in advance!

Humm... I might go TosLink between the iMac and the FastTrack and then run the USB connection to the MacBook Pro when your using it in Target Display Mode.
Or vise Versa, leave the USB connected to the iMac and use the TosLink connection for the MacBook Pro.
See > NewerTech CBLAOPTMT Toslink to Mini Toslink Optical... in stock at OWC

Brightness iMac in target display mode: who has it working in 10.6.8?

"With Target Display mode, you can use your iMac (27-inch, Mid 2010) or iMac (27-inch, Late 2009) with Mac OS X as an external display.": http://support.apple.com/kb/ht3924 . "Use the keyboard of the 27-inch iMac to adjust display brightness and sound volume and to control media playback of applications running on the 27-inch iMac in Target Display mode."
This used to work perfectly for me. But under 10.6.8, the brightness control stopped working. Sound and media control still work as expected. I posted before on this.
Now I know more people are experiencing this problem... I am looking for people who DO have it working under 10.6.8!
I'm looking for anything I can do to get it to work, maybe the info from people who have it working gives me some clues.
Lion is just around the corner. Please let me know if Lion fixes this problem for you.
Thanks!
Maarten

I'm using two 27" imacs and one of them is still on 10.6.8 one has been upgraded to Lion just now.
I thought it was the Lion update which caused this issue for me because I installed 10.6.8 on both of them today as well.
Now I can't adjust the brightness in target display mode on either 27" imac.... worse that that it sets it to full brightness too.
I don't know of I want to try to go back to before 10.6.8 with time machine, talk about gutted ?
can you use monitor calibration as a work around ?
I found TS3919 but it doesn't work BTW , it says to set the brigthness before entering target display mode..
Simon

No backlight in Target Display Mode on 2012 27" iMac

I am trying to use my new 2012 iMac 27" as an external display for my mid 2011 Mac Mini with Target Display Mode. At first it seems like it's not working when switching as I hit Command + F2 and the screen changes to black. But after shining a flashlight onto the monitor I can see the desktop and dock of my Mac Mini operating system. Mouse control and everything else works, it's just the backlight doesn't light up when connected to the Mac Mini. But hitting Command + F2 again brings it back to the iMac and a normal functioning backlight.
I'm assuming this is a bug in the new iMac because I had a late 2011 iMac 27" (previous generation) hooked up to this same Mac Mini and Target Display Mode worked perfectly between the two. It was even the same exact Thunderbolt cable. I have re-tested the Mac Mini and plugged it into another monitor with a DVI to Mini Display port adapter and it has worked fine. Has anybody else experienced this behavior?

HI - i had this problem too. see my previous post above. I spent weeks on the phone to apple support.
from memory:
1. I had to reinstall the OS (from a download) - but this failed to work
2. So... I had to perform a complete reinstall of the operating system (and wipe all user data)
3. and then restore all my user data.
Everything has worked seamlessly since then - which to me indicates it's a s/w problem and possibly one with something in my user profile? I just reliased I did not try and create a new user and try TDM using that. This would've proved it was a user profile problem or not.. I had one small ocassion where the screen went blank a week ago, but I just quickly pulled the TB cable out and put it back in again - and it was all ok.
So in essence I've been runing OK now since I did the reinstall and restored the user data.
Richard

How can I make an external monitor the main display?

I have a mid 2007 iMac running OS X 10.4. The internal monitor is broken and all it shows is a bunch of lines.
I have connected an external Samsung monitor. All I see in it is a desktop background: no icons, no menus, no dock. I believe this is because the display is in extended mode and the main display is the internal monitor. I cannot use the System Preferences Panel to change this, because the internal monitor is useless.
I have a second, newer iMac, from which I can login to the first via ssh.
Is there a way to make the external monitor the main display from the command line?
(I have though of editing the Preferences List, but I do not know what to change and how to change it. I do have Developers Tool installed and thus can access the Preferences List Editor.)
Thanks in advance!!!
Gustavo J. Mata

Hi everybody!
To solve the problem I wrote a script that creates a Systems Preferences windows which shows up in the external monitor. Once this happens the configuration can be changed manually, to make the external monitor the main display. This is what I did:
First I created a user with automatic login in the faulty machine. To do this:
1.- Restarted this malfunctioning iMac in Firewire Target mode.
2.- Rebooted the working iMac using the other machine as startup disk.
3.- Created the user.
4.- Restarted both machines normally
Next I wrote a script which opens System Preferences and shifts its window to the left:
5.- In the working machine I saved the script as a 'Run only' application:
tell application "System Preferences"
activate
set x0 to 1080
set y0 to 200
set dx to 800
set wx to 600
set wy to 600
set the bounds of the first window to {x0, y0, x0 + dx + wx, y0 + wy}
end tell
6.- Then uploaded it to the iMac with the faulty screen.
7- Shut down both machines.
Then I added the script application to the automatic login user in the faulty machine:
8.- Restarted the malfunctioning iMac in Firewire Target mode.
9.- Rebooted the working iMac using the other machine as startup disk.
10.- In System Preferences added the script to login items.
11.- Restarted both machines.
The System Preferences window now showed in the external terminal. I was able to go into the Displays pane and set the external monitor as the main display (dragging the white bar to it).
Cheers,
Gustavo J. Mata

Dec 2012 iMac using bluetooth keyboard will not exit Target Display Mode

Hi! I have a new 27" iMac that I would like to use as a second monitor for my work laptop a late 2011 15" MBP. iMac is on 10.8.3 and Mac Book Pro on 10.7.5. Connected via a thunderbolt cable.
I can toggle on Target Display Mode using the command-F2 keys on my bluetooth keyboard connected to the iMac. If I understand directions correctly, I should use the same keys and keyboard to toggle off – but it doesn't work. I'm able to work around by putting MBP to sleep, which exits the iMac out of TDM.
I can use the work around, but...
1) it's annoying.
2) If I can't use the bluetooth keyboard to toggle, it would be nice to connect it to the MBP for use while in TMD. Unfortunately, the bluetooth keyboard is undiscoverable, presumably because it's still connected to the iMac.
I wonder:
Am I doing something wrong trying to toggle out of TMD using bluetooth keyboard?
or
Is there a way to enter iMac into TMD without using keyboard command? Maybe System Preferences?
Thanks for your help in advance!

Here's the solution: I had the same problem using my 27" iMac as an external display. The issue is, when you go to Target Display mode, your target computer, the iMac 27" locks the screen with your password.
To switch off TDM, type your password in on the iMac keyboard and press the enter key.
Now press COMMAND - F2 and the displays with switch back to two separate displays. :-)
I had to think like a computer to figure that out but it makes sense.
I also have the disappearing mouse pointer and have not figured that one out. I did all the software updates and I did not have this problem until I upgraded to Lion. It is definitely a software issue. I might have to open a case with Apple support. Not happy.
Derrick

Apple Mini DVI to DVI Adapter to connect Win7 tower to iMac / Target Display Mode

I currently run Windows on bootcamp on the iMac (Mid-2011), although the tasks I perform (3D modelling, rendering and such) cause the Mac to get very hot, and as a result hae a slight burn mark on the LED LCD screen.
I am buying a Windows machine, and am to uninstall bootcamp and use the Mac purely for OSX, but use the iMac screen as a monitor for the tower using Target Display Mode. My issue is - the Windows 7 tower only has DVI output. And as I understand, the Mid-2011 iMac only supports Target Display Mode via a thunderbolt cable.
My question is - Will the Apple Mini DVI to DVI adapter allow me to connect the DVI-only tower to the iMac? Thanks in advance x

Oh, I should mention also that the iMac is the 27" model. Mid-2011 3.4Ghz Intel Core i7 with 4GB RAM and 1TB Harddrive. And ATI HD5450 1GB Graphics.

Can windows 8.1 in boot Camp display in target display mode on an IMac?

I have given up on Windows 7 running in Boot Camp on my 15" MacBook Pro and displaying it on my 27" IMac via thunderbolt and Target Display Mode.
The FAQ concerning Target Dsiplay Mode farily clearly says Windows 7 won't work.
But it does not say Windows 8.1 will or will not drive Target Display Mode via thunderbolt.
see: http://support.apple.com/kb/HT5219, question 29
Has anyone found that running Windows 8.1 in BootCamp on a MacBook Pro Retina mid 2012 will display via a thunderbolt cable in to Target Display Mode on a late 2013 IMac 27"?
I don't want to go to the trouble of installing Windows 8.1 and trashing my otherwise functional Windows 7 Boot Camp installation unless it is going to display properly on my late 2013 27" IMac running OSX 10.9.3 via thunderbolt.
Thanks in advance!

no, tdm doesn't work under bootcamp regardless of which windows is being used, imho i don't think it will ever work under bootcamp

How can I use my 27" iMac (2010) as an additional display to my Windows 7 PC (target display mode)?

So I have purchased a windows machines so that I can play all my favourite games on, and it's not so much a problem rather I have a 27" iMac that I would like to use as an additional monitor for said games.
I have had a look at this article on using the iMac as a display for another computer and things looked promising. I think I need a bit of help getting there though as I can't find definitively anything online to tell me exactly what I need. Most stuff talks about connecting other Apple computers that have mini display ports.
My PC's video card is an nVidia Geforce GTX 650 Ti that sports 2 DVI ports and a mini HDMI port (adaptor to full HDMI was included). The iMac has a mini display port. I went out and got a HDMI cable and Moshi Mini DisplayPort to HDMI Adapter (with audio) to try to use the iMac as the additional display. I connected the PC with [a generic] HDMI cable to the adaptor which ran to the iMac and went through the appropriate steps (ie. pressing CMD + F2) to initiate target display mode. Nothing happened.
I have read that other people with different situations tried an SMC reset, but this didn't work for me either.
At this stage I wanted to see if the DVI port would do anything, or perhaps looking at a particular kind of HDMI cable, but wanted to see what the community can offer up as advice.
Any assistance would be greatly appreciated.
Thank you.

Hi,
have a read here http://support.apple.com/kb/HT3924
Regards
Stefan

External Monitor in Target Display Mode Won't Wake Up

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