my macbook pro does not detect external display anymore

It's getting weirder and weirder:

I figured out that I can still use the VGA signal. If I hook up my external monitor using a DVI -> VGA adaptor, I can use it. The image is not as crisp as with DVI, but no big deal.

This week I had an OS update (to 10.7.4) and because I think it's still possible that this is a software issue (in combination with this particular model MBP, 15-inch Early 2008; 2.4 GHz Intel Core 2 Duo; NVIDIA GeForce 8600M GT 256 MB) I tried after installing the update.

And behold: DVI worked again. At least, for as long as it took to disconnect the VGA cable and get ready for work - and then the screen blacked out again.

So it's back again to VGA.

Sigh. 😟

This worked for me:

My external monitor worked fine for over a year - until I've installed Diablo 3 (game) and turned on "Anti Alising". I turned it off and voila, my mac detected my monitor again.

I am having the exact same problem and your solution works perfectly! Thank you so much!

Solved problem of HDMI connector not working with Mac laptop (at least for today).

Had issues with new MacBookPro connecting to ViewSonic 22" monitor with miniadapter into HDMI. Spent 40 min online with Apple rep. I finally suggested trying my VGA adapter and cable and that worked. The rep then said it must be the mini adapter. Knowing that this same adapter and cable worked 2 weeks ago on my parents' TV with a visitor's Mac laptop, I took the cables and laptop to their apt, where it worked fine--so I don't need to buy another mini-adapter. Came back to my adapter and now it works!! Don't know if getting it running on another monitor did something to reset the laptop, but am happy I can now work!

Did notice in changing something else that just barely moving the monitor (to get behind it) made the signal go away. Moved it again and it came back!! (Sounds like a ViewSonic problem.)

Hi

I have many of the problems discussed here with my MBP 2011 and a 20"SyncMaster205bw.

This morning there was an update for the Thunderbolt available. I upgraded and all worked well. But I am not shure if the misbehaviour will not begin again.

After a little googling I found that there is a service in Lion named "detect display" with a keyboard shortcut of cmd-shift-E. I changed it in Automator to respond on Text and in Finder.

When I have the situation with a black or unresponsive screen, I can type cmd-shift-N to get a new folder. This one has the name field selected. So the services in Finder for text are available. Typing the shortcut for the "detect display" services runs this app and brings my display back. - I added a part to the applescript of the service to delete the new folder before quitting.

A very dirty hack, but it will save my time until Apple is able to fix that problem.

My script snippet in the Automator service: (The words in german must be translated)

on run {input, parameters}

tell application "System Preferences"

set current pane to pane "com.apple.preference.displays"

end tell

delay 1

tell application "System Events"

set the visible of process "System Preferences" to true

if UI elements enabled then

tell window 1 of process "System Preferences"

click button "Monitore erkennen"

end tell

end if

end tell

tell application "System Preferences" to quit

tell application "finder"

try

delete folder "Neuer Ordner"

end try

end tell

return input

end run

Another possibility is to save the script as a program an put in into the dock. Hitting F3 shows the dock and the app can be run.

Ruedi

I'm having the same issue. I just ordered a new monitor today thinking that was the problem after my Dell external worked splendidly for years. Then I had a hunch, hooked said monitor up to my old Dell laptop and it worked like a charm. Too bad I can't cancel the order. Then I ordered a new mini-DVI to AVG connector in the hopes my connector is bad. That hasn't arrived yet, so the jury is still out on that. However, the Dell monitor is detected in settings, it just won't turn on. The power flashes at me as it mocks me, but it won't actually work. I've downloaded fgxCardStatus and changed the setting to discrete to no avail. This all started around the time of the update to 10.7.4. Do I bother going to the genius bar? I have a 2009 MBP which is out of warranty. I'm torn between however much the geniu bar will charge and putting that toward an iMac. I'm a copy editor by trade. The small screen is giving me a headache. Am I spoiled? yes. I also paid quite a bit of money for Apple quality and am feeling a bit let down at the moment. I saw a post for a script suggestion, but I'm honestly not computer savvy enough to attempt that. Any additional advice is appreciated. Thanks!

Daniell

To Daniell,

I see you are using the mini-DVI to AVG connector. Have you tried a mini adapter for an HDMI? If your monitor is new, I assume it has that. Also, mine got a "jump start" when I hooked it to a real TV, not just a monitor, thru the HDMI connection. Before I tried it on another TV, the monitor wouldn't turn on at all. After I connected it to a TV, it began working.

I notice, however, that I need to turn it out in this order:

1) Tell computer to Sleep (don't just close it)

2) Switch off monitor.

When I turn it on, I do it the opposite way--monitor first, then wake up computer. Sometimes, if the computer has been turned off, I have to click Detect Displays (black box at top rt of screen).

Hope this helps. (40 minutes on Apple Support line got me to "Well, your mini adapter isn't working." Since it had worked 5 days before, I suspected that was not the case, but it sure got the support guy off the phone!)

Dotshell

Thanks, Dotshell. My monitor is at least five years old. This is the only cable I have for it. I'm just so frustrated that it worked fine until a few days ago and now it's not. I'll see if the new monitor I ordered works. I'll try your suggestions for the trial run. If not, I guess I'll return it go to the genius bar. I'm concerned that they won't be able to help if Apple Support isn't acknowleding an issue that many of us seem to have. Thanks again!

Daniell

Putting the laptop to "sleep" and closing the lid before plugging in the monitor cable helped. The monitor is now displaying. However, I'm unable to change the settings to where it's supposed to be.

Daniell

I'm happy to say that my problem is solved!!! The simple fix for me was getting a new mini display adaptor. I'm so thankful it was something so easy and inexpensive! Shame on me for thinking that it was software issue. 😊

Had the same issue, same monitor. SwitchResX solved the issue...finally.

thanks!

PS. The adapter was not an issue since I was using original Apple product and the problem with the external monitos only started when I upgraded from MacOS 10.5.7 to 10.6.8

Hi everyone,

My solution was to use gfxCardStatus (free at http://codykrieger.com/gfxCardStatus) and to set the graphics to Discrete Only in both battery power mode and plugged in mode (set in the preferences pane). I have an early 2011 macbook pro 15" with a 2.0ghz i7, for the record, with the most up to date firmware and updates. When I switch it to integrated graphics, it immediately stops detecting the external display, and the external display goes to sleep and does not detect a signal. By the way, I am using a minidisplayport to vga adapter.

It's a shame that we need to fix this problem ourselves, Apple should have taken care of this.

Thanks to everyone who has posted solutions, and tips on here.

-Philosoraptor

This may help. I found this on the gfxCardStatus website:

"Why isn't my external

display working?

Don't worry - nothing is broken. If your external display is not being detected while you're using gfxCardStatus, it means that you have a newer i5/i7 model, and you're currently on Integrated Only mode. Switch to Discrete Only or Dynamic Switching to use the display. The Intel graphics chipset is incapable of outputting video through the Mini DisplayPort."

15in Macbook Pro - Mid 2009, 2.66GHz Intel Core Duo

NVIDIA GeForce 9400

I just purchased a 24in Viewsonic monitor to use with my laptop when docked (with Apple USB keyboard and Bluetooth trackpad). The monitor works great most of the time. But I would like to be able to wake up my machine using the keyboard and have the monitor wake up at the same time. However, at present, the laptop wakes up (I can tell by the change in the indicator light on the front of the closed machine) but the monitor doesn't. It will start working if I unplug the monitor and then replug it in.

Additional weird stuff happens as well, like my computer sometimes using my designated desktop image as the background, but most of the time is just displays the default pink nebulae/star image. There is no predicting when my own background will display and when it won't.

Some in the above thread commented that the adaptor might be a problem. I am using a mini-display port to D-Sub adaptor which obviously works great (I am using it right now), however the wake up issue is still a problem.

I also tried turning off anti-aliasing. WIth that feature disabled I was able to wake up my monitor with my laptop one time, but never again. I tried restarting after setting the anti-aliasing off, but it was right back to normal.

To Muddlingthrough,

Here's what works for me with my laptop: When you want your computer to go to sleep, turn off your monitor first, then manually click Sleep (instead of just shutting the lid if you have a laptop). When you start up, click ON the Monitor first, then open up the laptop. The order seems to matter. (Spent 40 minutes on the phone with Apple Support when I had this problem and they couldn't help me at all. I just did this by trial and error.)

dotshell