Patience seems to resolve the problem: after my post, I took a cup of coffee and then reconnected the monitor to the MacBook.
Lo and behold!
An image appeared on the monitor.
It looks a though the MacBook and the monitor are having timing problems.
On a few occasions, I noticed that the MacBook had detected an external display (I could move my mouse pointer off-screen) although the monitor complained about not getting a signal. On other occasions, the monitor went into what Iiyama calls "Power Management Mode". Some times the MacBook would still think an external display was attached, some times it didn't.
I can force my monitor to look for a signal (turning it off and then on, or by pressing the "Auto" button for a few questions.
But I cannot force the MacBook to detect the external display, not even with the "Detect Displays" option in the Displays section of the System preferences.
Since I hope Apple is reading this thread, I will post some more observations when my monitor does not display an image. That should contribute to a proper solution (i.e., one other than patience, trial and error).
Switching to Nvidia Only or Dynamic Switching enables the use of the external display again, see http://codykrieger.com/gfxCardStatus/faq#ext_display
This was exactly my problem, thanks a lot!
Started noticing issue over a month ago-- out ot the blue. Assumed it was a bad HDMI cable, but only after failing with new cable did I find this thread.
I have a 2010 MBP 13", and an LG 42pq10. Everything worked great up to some time in May,
--Tried resetting NVRAM, no good.
--Tried rebooting with screen on, and plugged in. No good.
--Tried installing gfxCardStatus (even though my machine is not supposed to be affected). It keeps telling me
'd' for 'discrete' GPU which is supposed to be the right setting for a working external display. (But, no working external display.)
--Noticed problem while running 10.6.7. Updated to 10.6.8 with no effect.
--My video card is an nVidia 9400M, so apparently should not be affected by the following issue:
Tried messing with various screen settings, screen just always says 'No Signal' even when System Prefs can detect the monitor and correctly guess resolution, and I'm playing with the "Arrangement"....
I guess the last thing to try is getting a "better" minidiplay-to-HDMI adapter, like they recommend here:
Will that really help? Other posts in this thread are not clear on the issue. I am loathe to spend $40 on a solution that *might* help (when I was fine before).
C'mon, Apple. This thread started in January. Where ARE you?
I guess I'm just hoping some other user will see this and it will spur him or her on to tell me their fix-- and that it magically works for me.
I have a mbp mid 2010 and I tried exactly the same as sammixalot. and even more:
- bought a new expensive adapter...wont work. thanks apple!
- tried it on my windows partion where it worked before....nothing.
how can that be true?
a few month ago everthing was working fine and now this?
this is ridiculous!
i hope this is not a kind of mean marketing to make us upgrate to Lion which comes out in a few days...
i am soooooooooooooooo not happy with this situation.
please do something
I have the same problem. My MBP which is still new less than 4 month old cannot detect my external Samsung Display. It worked fine in the begining until it stopped detecting the external displays. I believe it was about the same time when there was a OS update. I hope the APPLE guys responsible for this, reveiew the problem and fix it ASAP in the next update.
My System is : MBP 2.7 GHz Intel Core i7
Current Os : Mac OS X ver 10.6.8
I am currently having the same problem. I have a Samsung TV Monitor and it has been working fine for around 3-4 months and this week it has decided not to connect. It comes up with a blue screen for 2 seconds then nothing comes up on my monitor, just says there is 'no signal'. Does anyone has any suggestions as to what the problem is?? i was thinking of buying a new Mini Dvi- HDMI cable but would this work?? This is so fustrating as im a Designer and working on a 13in screen is so limiting....... any suggestions....?????
I was having this issue and the only solution was another mini-dvi to HDMI cable. I am on my 3rd on and it has been a fauly cable each time. The cable wasmalfunctioning internally possibly because I disconnect mine so often. After buying my 2nd cable I had thought that it could not be the cable. i went to the genious bar and my computer worked connected to a number of external displays. When we tried my cable it did not and then we tried a new cable and viola. the Apple store replaced the cable free of charge and I have been using my external monitor now with no issues.
I have the same problem with my Samsung monitor doesn't detect the signal anymore. I tried turning on and off, unplugging cables, restarting the macbook to no avail. It's worked fine in the past but for the past few weeks, it's acting up and it's annoying.
Sometimes when i leave everything unplugged for a minute, then it'll work. I've also resetted my PRAM and it looks like it's working alright now.. But I hate to see this happening again.. Apple, please fix this issue
I have resolved my issue.......i took my macbook along with my mini DVI - HDMI cable with me to the Apple store.
They plugged my mac into a screen using my wire and it was having the same problem.
Then they got a new wire out and plugged my laptop to their screen and it worked :-) !!!!
So therefore in my case it was a faulty wire and now it works perfectly ...just like it used to :-)
Ive got the same problem.
I have a Macbook Pro,
Ive always had it plugged to my Samsung LCD TV and has always worked until I took it back to my parents and connected it to their LG monitor. It worked perfectly. after returning home and connecting it back to my Samsung, I found that I could not get a signal. The screen goes blue for a second but nothing after.
Ive checked the profiler and it states its running the Nvidia GT 330M and not the built in intel video card.
Sorry, this is overdue, but I did solve this issue.
(Had some issues with my mac support sign-in, but I am actually one of the people earlier in this thread.)
What can I say? $30 at the Apple store on this...
and everything worked out. <edited by host> but I wanted to be done with it. I think it had something to do with apple including sound on their minidisplay/video-out spec, and my old adapter was a cheap (~$10) alternative that worked until that inclusion.
So, <edited by host> to Apple. Annoyed that the solution was merely giving them and Belkin $30+ bux. <edited by host>
I can, however, now watch a Stephen I actually respect (Colbert) on my big plasma again.