Q: my macbook pro does not detect external display anymore

I bought a new Rocketfish to hdmi adapter thinking my Moshi had broken. This did not help at all. I tried the disk permission repair, opening, closing, rebooting, unplugging and nothing works. At this point I am just considering selling my macbook and buying a different computer. What is the point of having to switch to a VGA when HDMI is so much better quality. It worked before and should continue to work.

I tried the HDMI first too... didnt work...  it used to... it just decded it didnt want to play ncely with my macbook, but the VGA does and I sure don't need a new computer just to plug in an external monitor. VGA looks just fine to me

Hi All,

I've had my own experience with this problem, which I solved for my situation partly because I read all 17 pages and got ideas. So I wanted to share what I learned so that some of you might benefit. Others may not, becasue it's obvious that what worked for some doesn't work for all. Also, I wouldn't rule out a role for superstitious thinking and coincidences as well.

I'll try to be concise and brief.

I have a late 2008 2.53 GHz 15 inch MBP with 4 GB of RAM, and the video is NVIDEIA GeForce 9600M GT 512 MB. This machine has been through a number of system upgrades and inherited data via migration from several previous machines. I have never done a clean install, so there are lots of possibilities for troublesome things hanging around on the disk.

I use it as a desktop with an external monitor most of the time and then disconnect it and take it with me when I travel. Until last year I used it with an older Apple Studio Display from 1999 without any problems. In order to do better photo editing I upgraded to a 24" Eizo CG223W with 1680x1050 resolution. It is connected with a minidisplay port to DVI converter. Again, no problems.

Earlier this month, having already upgraded to Mountain Lion, I installed the 10.8.2 update. Shortly thereafter I began to notice bad behavior, first problems waking from sleep and then, much worse, worsening slow performance so that I spent a lot of time looking ar beachballs or even just waiting while staring at nothing.

I made a short trip and took the laptop with me. In the hotel room it ran totally normally, although it still had the waking up problem.

When I came back I reconnected and began going through many of the steps recommended in this thread and others. That included going to Safeboot and repairing the disk (there were some issues), resetting nvram twice, and then resetting SMC by taking the battery out and holding down the power button.

When I reconnected to the external monitor I was unable to get the display to work correctly. First there was an annoying flicker that made work impossible, then intermittent blanking out, and then mostly a blank screen with the monitor indicating there was no signal. But when I lifted the lid and checked display preferences the computer knew the monitor was there and allowed me to change alignment and so on. On a tip from this thread, I reset the resolution on the external display down two steps, which put it below the resolution of the laptop's screen, and the monitor went on, functioning normally. However, that was unacceptable for photo work.

I was pondering doing a clean install but it's a lot of trouble, I was worried about a backup miscue, and there were messages to the effect that it didn't solve the problem anyway.

After a couple of days of stewing and trying different things, which if anything made it worse, I was reading the messages about gfxcrdstatus. A light bulb popped up in my head about something I dimly remembered seeing. I went to energy saver preferences and under battery there was a choice of two options under "Graphics," Bettery battery life and High performance. Guess what? The first was selected. When I changed it to higher performance and then reset the Eizo to its full resolution I was rewarded with a crisp, clear high def screen as I had enjoyed before all this mess. This was basically, I presume, the same thing that gfxcrdstatus does. Two days have gone by and it remains normal. Also, the slow performance was totally fixed and everything is fast, maybe more so than before. As an aside, I reset the sleep parameters to default and that problem is resolved also - the sliders for screen and computer were different; perhaps that was the problem there.

Hope this helps somebody out.

Ed Merrin

Ed I was able to get my Westinghouse to show up under screen detection with your solution but it doesn't give me the option to select it, it is gray instead of black on drop down menu. TV still reports no signal.

Well, I tried most things for this and thought I had cracked it using SwitchResX, but the problem of my Samsung hdmi linked monitor going blank was still there.  so the only thing I have done, which to date has "cured" the problem- 8 bought a cheap minidisplayport to HDMI adaptor from the web.  So far so good, for £6.   Will post again if it also fails, maybe the apple adaptors a just too sensitive?

Had the same issue - ACER monitor just stopped working with my mbp, had a Moshi mini adater HDMI connector and was working fine, then one day just stopped - tried other cables and nothing worked - installed gfxCardStatus and saw it swapping chips OK.

Turns out the Moshi connector had broken but in order to get the other cables to work I had to log off the mbp - I wasnt doing that at first, just swapping one cable for another and getting no where.

Ordered a new cable (no adapter) from Amazon.

Took me 2 months to work that one out !

Not sure if I understand your message. When I pull up energy saver preferences I don't see anything related to a specific monitor or screen. There are two options, battery and power adapter that access controls for display and computer sleep for each power source. Then there is graphics in the upper left corner, either battery saving or high performance. They will be greyed out if you haven't clicked the lock to make changes. Otherwise, I wonde what rgaphics card you have.

I was actually trying everything for over 3 hours, and I finally reproduced the exact steps described by SanctionOne. I was trying similar things, but the key is having the adaptor and cable plugged into your laptop and then closing the lid before connecting to the display. I just connected to an LG TV, and before this, I was not able to connect to any screens, projectors, tv's for nearly 4 months.

I have a: MBP, 13-inch, Mid 2012, running Mac OS X Lion 10.7.5 (11G63b)

Thank you very much SanctionOne. For those who didn't see the post, here it is:

SanctionOne

Okay,

I originally posted a response to how I have solved this with my setup and ill repost it here...

You have to unplug the power cable from the syncmaster... then plug in the mini diplay adapter... then do a "detect display" is system preferences to check to see if it's detecting it...  then simply close the lid to the laptop and plug in the power to the syncmaster... it will "detect" the monitor and it comes back every time for me now... I've dealt with this issue for over a year.... but it's how I get my external monitor back up every time.  Apple and Samsung need to get together and fix this but until then it's the only thing that has worked for me...

However, people seem to still have issues following this so I have went ahead and put together a video as well...

You can view the YouTube video I've made here... http://www.youtube.com/watch?v=41tfRsfNU0A

This is what I have to do everyday to get my Macbook Pro to redectect/recognize my Samsung Syncmaster External Display....

Hope this helps some people.

Message was edited by: austhehaus22

edmerrin wrote:

 

Earlier this month, having already upgraded to Mountain Lion, I installed the 10.8.2 update.

 

I went to energy saver preferences and under battery there was a choice of two options under "Graphics," Bettery battery life and High performance.

Ed I also have 10.8.2 but in System Preferences>Energy Saver>Battery I don't have any Graphics options? I can tell my display when to sleep and I can choose to slightly dim it when using battery but that's it.

Hmmm. When I choose energy saver I get a window that has two sliders, one for computer sleep and one for display sleep. There are two buttons above that for battery and power adapter. Which one of those you choose determines options that appear in the lower left. However, the graphics options are visable in teh upper left of the window regardless. They are greyed out if the "padlock" at the bottom is closed.

If you don't see the graphics options and you have the same software version, that raises the question of what might be different about the computers. Could it have something to do with what kind of video chip is installed? What type of CPU? What kind of connector? Perhpas soeone else here knows. All I know is my problem is gone. When I travel I'll probably set the graphics back to "Better battery life" and then I'll have to remember to set it back to "higher performance" when I hook it back up to the external display.

There's gotta be an explanantion.

Ed Merrin

i have a panasonic viera too and it was working for the first two or three times and then stopped working as well! thought it was the cable or adapter so i bought another one of each and still no resolution... then thought it was the thunderbolt port and it worked in the apple store via a thunderbolt to dvi adapter but still wont work with either of my thunderbolt-hdmi adapters and hdmi cables! so annoying!

ive had the same issues as you have with a panasonic hdtv ... so freakin frustrating!!!! did you ever get a fix? im still reading thru this entire thread .. its pretty long..

I have a similar issue but restarting the computer just froze. Can´t even connect a video projector as well. It seems that when i changed the settings on the video resolution, it just got stuck there. Now a have a MB that i bought for VJing that doesn´t work with vga connections!!! This is a serious issue!!! Why is there not and update APPLE????? Any one there????

I am as frustrated as others within this topic. I installed ML, and for awhile I was able to connect my TV monitor to my MacBook Pro (2009) using a MiniHDMI cable. Then "poof" no longer. My Sony Bravia can no longer detect the signal from the MBP using the same cables as before. Within the timing, this occured after an ML update.

It is my hope that Apple will fix this issue and is not a ploy to market their Apple TV...

I am tempted to unintall ML and go back to Snow Leopard...there were never any issues with SL OS

I becoming more and more frustrated with these issues. I propose everybody to use this blog and inform your community through twitter about this problem that Apple has to fix.

I'm realy considering to quit with apple computers.

you can see my twitter anouncement on @janwillemtromp