HMDI Connected External Monitor only works mirrored

I've got a 27-inch iMac with the 2.93 Ghz Intel i7 (running Mac OS X 10.6.5) connected to a Hannspree HF289H 27.5in external monitor (1920x1200 resolution, connect via Mini Display to HDMI adapter and an HDMI cable). It has worked fine for a few months, but all of sudden the 2nd monitor will just go black. When I restart the computer, the 2nd monitor will flash on and off and resize, but will not show anything once the computer fully comes up. If I go to the monitor settings and choose to "mirror" the display, it comes on and works. Then, if I take it off mirrored, it will work for a matter of minutes to hours, but eventually go black again.
Any thoughts? I've already tried resetting the SMC and restarting with a PRAM reset as mentioned in other posts.

Are you using the method in this Apple article? If you do, it should work.
Mac notebooks: How to use your computer in closed clamshell (display closed) mode with an external display

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External monitor only works with clam shell open

external monitor only works with clam shell open

Are you using the method in this Apple article? If you do, it should work.
Mac notebooks: How to use your computer in closed clamshell (display closed) mode with an external display

Strange issue with external monitor, only working when external speakers plugged in (using Thunderbolt to VGA adaptor)

Hey – I am having a very strange issue with my external monitor; where it only works if my external speakers are plugged in and connected.
I am using a late 2011 Macbook pro, running Mavericks 10.9.4, along with an MBox 2 (USB Audio Interface), and two powered speakers (KRK Rokit 5). This setup has had no issues. I have just acquired an external monitor (Benq T2200HD), which I am using with a thunderbolt to VGA adaptor (a cheap Chinese knockoff adaptor).
To start - I plugged the monitor in with the thunderbolt adaptor, and it powers up and works fine. However, there is a nasty buzz coming from the speakers. I did some research and it looks like a simple ground loop issue. I did a bit of troubleshooting, and this is where things get weird.
What I found is - If I unplug the MBox, the monitor loses signal from the computer (displaying ‘No Signal Detected!’). Further, if I keep the MBox plugged in, however unplug both the cables from the MBox to the speakers, the monitor loses signal. It doesn’t matter if the speakers are turned off, however they need to be plugged in (or the monitor loses signal). Weirder still, I can unplug the MBox, however the monitor will work if I plug in the speakers through my macs headphone jack.
Simply put, the monitor only works if there is a direct connection between the computer, the speakers, and the power source. What is going on here? Is the monitor grounding through the computer port, to the speakers (I don’t know how this works, is this possible?). Could it somehow be the cheap VGA adaptor I am using?
Some other information:
- Everything is plugged into the same multi-box for power. I have tried plugging things into separate sources, and the result is the same.
- If I unplug the thunderbolt adaptor, then the speaker noise disappears straight away.
- The ground noise doesn’t appear in my headphones, which are plugged into the MBox.
Any information would be great – am I missing something here, or is this genuinely weird?

Well, I went back into Best Buy to test on 3 other laptops (2 Asus, and their floor model for this Sony). It seems to be doing the same problem so at least I was able to rule out broken hardware issue on my particular laptop.
Here's what I did to test:
Since I couldn't really install Adobe Premiere on their machines, I used the DVIO software (http://www.carr-engineering.com/dvio.htm) and a 5 min clip I captured. I transferred onto their machines, hooked up my Sony D8, and attempted to play the video. It would play for 15 seconds and then stop and jitter with a loud noise (like it does on my laptop). I even tried changing each machine's firewire driver to the legacy one and same results. I pulled a brand new 4 pin to 4 pin firewire cable off their shelf and still the same problem.
I think I've nailed it down to Win7x64 bit Home Edition not playing nice with Firewire driver. Very annoying. I can't find any concrete evidence of this from other users on any of the forums that have my particular problem, but from my own testing, it's all I can conclude.
I have 2 other things I can try:
1. Opening the laptop and looking at the firewire to maybe find appropriate driver (ugh, I don't want to have to open this thing up).
2. Upgrading to Win7x64bit Pro and possibly testing with XP on the new MS Virtual PC (http://www.microsoft.com/windows/virtual-pc/). I can't do it with my Home edition apparantly.
Who needs to view video on an external TV anyways....sheeesh...(scarcasm).
Tim

Strange issue with external monitor, only working when external speakers plugged in

Hey – I am having a very strange issue with my external monitor; where it only works if my external speakers are plugged in and connected.
I am using a late 2011 Macbook pro, running Mavericks 10.9.4, along with an MBox 2 (USB Audio Interface), and two powered speakers (KRK Rokit 5). This setup has had no issues. I have just acquired an external monitor (Benq T2200HD), which I am using with a thunderbolt to VGA adaptor (a cheap non-apple adaptor).
To start - I plugged the monitor in with the thunderbolt adaptor, and it powers up and works fine. However, there is a nasty buzz coming from the speakers. I did some research and it looks like a simple ground loop issue. I did a bit of troubleshooting, and this is where things get weird.
What I found is - If I unplug the MBox, the monitor loses signal from the computer (displaying ‘No Signal Detected!’). Further, if I keep the MBox plugged in, however unplug both the cables from the MBox to the speakers, the monitor loses signal. It doesn’t matter if the speakers are turned off, however they need to be plugged in (or the monitor loses signal). Weirder still, I can unplug the MBox, however the monitor will work if I plug in the speakers through my macs headphone jack.
Simply put, the monitor only works if there is a direct connection between the computer, the speakers, and the power source. What is going on here? Is the monitor grounding through the computer port, to the speakers (I don’t know how this works, is this possible?). Could it somehow be the cheap VGA adaptor I am using?
Some other information:
- Everything is plugged into the same multi-box for power. I have tried plugging things into separate sources, and the result is the same.
- If I unplug the thunderbolt adaptor, then the speaker noise disappears straight away.
- The ground noise doesn’t appear in my headphones, which are plugged into the MBox.
Any information would be great – am I missing something here, or is this genuinely weird?

Hello cgoldberg11
Please go to the below link to test if you are having a speaker hardware failure.
Testing for Hardware Failures (Windows 7)
This will rule out hardware failure, let me know how that goes.
Thanks
If I have solved your issue, please feel free to provide kudos and make sure you mark this thread as solution provided!
Although I work for HP, my posts and replies are my own opinion and not those of HP. .....
Reguards,
Mo

Extern monitor only when connected?

hi, i have a big problem, i have a macbook pro 3,1 running arch with nvidia driver, and i have an extern monitior, which i want to use, if plugged in on dvi.
i want to use the extern monitor only, no macbook screen, i know i can enable the monitor with nvidia-settings, but when i shutdown, disconnect the monitor, and for example have a journey with the train, then my macbook cannot be used, because the configured screen is the extern monitor, and the macbook screen is black. no hotplugging here
if theres no clean solution for this problem, maybe there is a cmd to switch to external monitor only, which i can enter manually every time i need the extern screen, and after reboot it switches back to macbook screen?
i hope someone can help me....
regards chief

You can try something like this in your .xinitrc
xrandr | grep DVI | grep " connected "
if [ $? -eq 0 ]; then
xrandr --output LVDS1 --off
xrandr --output DVI --auto
fi

How connect External monitor to iMac?

How connect External monitor to iMac?

How to do that depends on the iMac variant you have. iMacs have been in continuous production since 1998 in four broad families that are not 100 percent alike in behavior.
Please look at the iMac images and descriptions in the links on this site:
http://www.everymac.com/systems/apple/imac/index-imac.html
and tell us what variant you believe you have.
iMacs from the first through third-generations (G3, G4, and G5 processors) that support an external monitor were not set up to do anything other than "mirroring"--you see on the external exactly what is on the built-in display.
Your description sounds like you have a newer iMac than this forum covers because, starting with the Intel iMacs in 2006, external monitors were allowed to do both mirroring and "extended desktop." The latter is what I believe you are seeing.
Try this first: press the F7 key. On many Macs capable fo using external monitors, this was a shortcut to toggle between mirrored and extended display. If your keyboard has an "fn" modifier key, you may need to press that to get the F7 key to work.
If you have an intel-powered iMac I can ask the Hosts to move you to that forum, which is much more active than this one which is for pre-2006 iMacs.

Thinkpad T60p with Win XP - Lost color on external monitor (only black & white)

Hi, I have a ThinkPad T60P, and a couple of weeks ago, I lost color on my external monitor (connected by VGA cable)
I have done a lot of testing, and found a couple of strange things around this:
* when using docking station with two monitors, only monitor nr "1" inCatalyst Control Center shows colors, but not "2".
* When using external monitor (or projector) I don't get color
* When showing video on the external monitor, color works(!) This is only on some type of videos, I think. Flash videos (ie. YouTube does not show colors)
* When getting a bluescreen, the external monitor displays bluescreen with colors. When rebooting after bluescreen, colors were working while booting (windows logo with colors), but as soon as XP was up, colors were gone(!)
* I have tried updating to the latest graphics driver (79d533ww.exe), and all the settings in Catalyst Control Center / Control Panel
As a result of these findings, I beleive it must be a software problem, but since upgrading the drivers didn't work, I don't know what to try next.
I see also that there are other people experiencing the same problems, but I can't find any solution to this problem.
Re:
http://forum.notebookreview.com/showthread.php?p=3597258
Hope someone can help me here!
Best regards,
pmlovold

Cats seem to have a strong affinity for that display mode — remarkably often we hear that they've typed in the correct keystroke combo for it, and yet they never seem to set it back to normal after using the computer. Not very considerate, but you know cats: consideration isn't part of the package.

VGA Port stuck on connected external monitor.

Lenovo G580, Win. 8.1 with all updates.VGA Port stuck on connected external monitor.Connected to external monitor via vga; "duplecate", "extend", and "second screen only" all works fine.When I return to default PC screen it too works fine; however, if I unplug the vga cable the default screen goes black.I tried restarting but it did not fix. Defult screen will only work if vga is pluged in.Any soloutions?

Hi JohnD7,
Welcom to Lenovo Community Forums!
Make sure that the Main LCD isused as the main LCD.
Open Screen resolution page
1. In the first box select your Main LCD
2. A Box below should appear, Place a check in Make this
hit Apply and try unplugging your external VGA
Let me know if this works for you
Cheers!
Solid Cruver

2010 Macbook Pro 17 display on external monitor only after power on

THis has happened a few times over the past 6 weeks - I power on first thing in the morning and the primary screen is black, and the login screen appears on the external monitor. Shutting it down and starting up again does the same thing. When it happened before I'd power off, remove the external display, power on and then I'd get the primary display back agin but it's not working this time and I've only got the external display working.
Is there a utility to 'kick' the graphics into the correct mode, or is this some type of hardware problem?
Thanks,
Graham

The primary laptop monitor starts blank, and only the external monitor is working.
If I shutdown, unplug the external monitor and power back on the laptop screen stays blank. If I plug the external monitor in the screen that would normally have been on the primary laptop screen is on the external monitor, and the laptop screen remains blank. At this point I can only work with an external monitor plugged in, and that limits my portability a bit

External monitor stopped working after 10.6.7 update

I have a MacBook Pro, model identifier MacBookPro6,2 with an NVIDIA GeForce GT 330M.
When I updated last night from 10.6.6 to 10.6.7 I stopped being able to use my Dell S2409W external monitor.
I have tried resetting the pram, resetting the SMC, booting with extensions off.
When I plug in the cable to the external monitor the Mac screen goes blue for about 0.5 second and re-appears but nothing displays on the external monitor; a second monitor is not listed in the Display preferences and the monitor reports that it is not receiving a signal.
I don't see anything in the system.log when I plug or unplug the monitor cable (I'm not sure if I should).
At random intervals while the external monitor cable is plugged in the screen goes blue for a half second and then re-appears.
The screen does not go blue if I wiggle or flex the monitor cable.

I see this in the windowserver.log after reboot, login with shift-key, and the external monitor connected.
There might be a clue here but I don't have anything to compare it to since I haven't collected these data when the external monitor was working.
I'd be curious to see the same data from the windowserver.log for somebody else with a MacBook Pro with an external monitor connected that does work.
You can view this log with the console application located: /Applications/Utilities/console.
If you are willing to share these data please reboot, and hold the shift-key down when logging in to disable extensions (thanks). If you look at the time just when the desktop appears when you end up looking at the windowserver.log you'll be able to see the windowserver starting up about 10 seconds prior to this time.
Mar 22 21:31:26 [110] Server is starting up
Mar 22 21:31:27 [110] CGXMappedDisplayStart: Display0 : boot screen
Mar 22 21:31:27 [110] CGXMappedDisplayStart: Display0 : display alias 0x0 valid
Mar 22 21:31:27 [110] CGXMappedDisplayStart: Display1 : no display alias property
Mar 22 21:31:27 [110] CGXMappedDisplayStart: Display2 : display alias 0x0 valid
Mar 22 21:31:27 [110] MPFinalizeInitialization: Display 0x3f003e unit 2 alias mask 0x5
Mar 22 21:31:27 [110] MPFinalizeInitialization: Display 0x4272dc0 unit 0 alias mask 0x5
Mar 22 21:31:27 [110] GLCompositor: GL renderer id 0x01022612, GL mask 0x00000003, accelerator 0x00003137, unit 0, caps 0x00000003, vram 512 MB
Mar 22 21:31:27 [110] GLCompositor: GL renderer id 0x01022612, GL mask 0x00000003, texture units 8, texture max 8192, viewport max {8192, 8192} extensions 0x0000000f
Mar 22 21:31:27 [110] GLCompositor: GL renderer id 0x01024300, GL mask 0x00000004, accelerator 0x00003c0b, unit 2, caps 0x00000003, vram 288 MB
Mar 22 21:31:27 [110] GLCompositor: GL renderer id 0x01024300, GL mask 0x00000004, texture units 8, texture max 8192, viewport max {8192, 8192} extensions 0x0000000f
Mar 22 21:31:27 [110] agc_attach: gMux mode is dynamic
Mar 22 21:31:28 [110] CGXPerformInitialDisplayConfiguration
Mar 22 21:31:28 [110] Display 0x4272dc0: MappedDisplay Unit 0; Vendor 0x610 Model 0x9cb7 S/N 0; online enabled built-in (0,0)[1680 x 1050], Rotation 0, base addr 0x102a00000
Mar 22 21:31:28 [110] Display 0x4272dc2: MappedDisplay Unit 2; Vendor 0x610 Model 0x9cb7 S/N 0; offline enabled built-in (2704,0)[1 x 1], Rotation 0, base addr 0x113800000
Mar 22 21:31:28 [110] Display 0x3f003d: MappedDisplay Unit 1; Vendor 0xffffffff Model 0xffffffff S/N -1; offline enabled (2705,0)[1 x 1], Rotation 0, base addr 0x102a00000
Mar 22 21:31:28 [110] Display 0x4272dc0: MappedDisplay Unit 0; ColorProfile "Color LCD" (MD5 a23cb9c96f2fd096b7a058db0d319259)
Mar 22 21:31:28 [110] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller (PID 202)
Mar 22 21:31:35 [110] kCGErrorIllegalArgument: CGXSetWindowListTags: Operation on a window 0x2 not owned by caller (PID 206)

Monitor only works in safe mode

My monitor only works in safe mode. when restart in normal mode the monitor screen is blank. when I start in safe mode the monitor works fine.

Is there a reason you have not entered the menu as I have suggested and reset the monitor to factory default?
Your old school monitor needs a kick in the pants to remind it that it is plug n' play. That is essentially what the reset will do. It won't hurt anything.
Was the TV you had connected to the PC before using the monitor an HDTV one with 1080p resolution?
In order to reinstall the graphics driver you will need to be logged in as a user with elevated (admin) priveleges. A standard user cannot install drivers or programs. You do not heed to reinstall RAID drivers.
You might need to consider replacing the monitor with a modern LCD display. They are quite inexpensive these days and can evven be found in the second hand market.
If you don't want to do that then you can remove the video card and then connect the monitor VGA cable to the video output port on the rear of the desktop PC. Removing the card will enable the onboard video.
****Please click on Accept As Solution if a suggestion solves your problem. It helps others facing the same problem to find a solution easily****
2015 Microsoft MVP - Windows Experience Consumer

External monitor not working - software upgrade

Use an external LG monitor with my Macbook at work - has worked like a charm. There was an Apple software upgrade this weekend - today, when I came back to work, I can't get my external monitor to work. The Mac doesn't see that it's there and the monitor's stuck in Power Save Mode.
Thoughts?

I have reset the PRAM and confirmed that the monitor and cable are functioning properly, but still no change.

Is there a way to connect and view an external monitor only on my Intel iMac?

I have an Acer 15.6" monitor connected to my Intel iMac via VGA cable and Mini-DVI to VGA adapter. I am running Lion (V10 7.3) and would like to direct my image to the external display only. The preferences pane does not offer that option. Is there some way to do it?

Do you have a desktop machine running iTunes?
If so then yes, setup home sharing and you can stream anything in your iTunes library to your iPad.
It works good.

Can't get external monitor to work

I've used a Mac laptop for the last 8 years, finally decided to get an external monitor for home use.
I purchased a 25" Hanns-G HZ251. It's not working as I would expect it to work. I've got a standard DVI connection on my older MacBook Pro so I'm connecting via a DVI to DVI cable.
The only way I can get the monitor to display what is actually on my laptop is to have my laptop open and mirroring turned on. I thought I could have my laptop shut and the monitor would still work when connected, but when I shut my laptop it just goes black.
If I leave my laptop open but turn mirroring off, I get the generic purple Mac desktop, not my desktop.
What am I doing wrong?
There's an install CD that comes with it, but that only runs on a Windows machine. I appreciate any advice, I'm fairly technically handy but this is my first foray into using external monitors, so I'm definitely struggling to figure this out. Thanks.

conejo61 wrote:
Yes, it's connected to the power adaptor and I have an external trackball and keyboard.
You will have to keep them both open and play around with monitor settings until you get them both working. Keep doing "Gather windows" in System Preferences to get the display preferences window for the 2nd monitor and change it each time it doesn't display anything.
I don't know what it means "you will have to set it".
You have to set the desktop for the additional screen. Once you get closed clamshell to work, the external monitor will be your primary screen and you won't have to worry about it.

External Monitor Not Working after 10.9.3

I have two Macs which are not working with an external monitor anymore through the thunerbolt port. I have tried different types of connections (HDMI and DVI) and two different external monitors in an attempt to determine the issue. The only common denominator to the issue is the update to 10.9.3 OS X. I have also reset PRAM and changed between mirroring and non mirroring to no avail.
Mac #1:
MacBook Pro8,1
Intel Core i5
2.4ghz
Intel HD Graphics 3000 512MG
External Monitor: Resolution 1920X1080 @60hz
32 Bit Color (ARGB8888)
Main Display: Yes
Mirror: Off
Online: Yes
Rotatino: Supported
Mac#2:
MacBookAir6,2
Intel Core i5
1.3ghz
Intel HD Graphics 5000
External Monitor: No information as it's not connected at this time.

Well low and behold I tried clearing PRAM again and I reset my monitor to factory defaults. Reconnected my monitor and the thing works now. Very strange but I'm Happy that it's working again. *WHEW*

HMDI Connected External Monitor only works mirrored

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