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my macbook pro does not detect external display anymore

i bought a new plasma panasonic tv one month ago and i have the adapter and everything.... i've also watched already over 30 movies by connecting my laptop with the tv through the adapter and hdmi cable... yesterday i was at a friends place and i connected my adapter to his hdmi cable and my mac detected his tv straight away but it didn't work . after this my friend told that he faced a problem with the hdmi cable(brand=hama) and he could not connect his laptop . after finding his tv and finally not working today i connect it to my own tv and the screen turns blue for a couple of seconds like trying to connect but does not detect my tv ... anybody has any idea what happened. my mini dvi port seems to work because the moment i connect the cable it turns blue( as when i was watching movies no problem)... now what happened ??

Message was edited by: giannisg

macbook pro 13,3 late 2010, Mac OS X (10.6.6), intel core 2 duo 2,4GHz , memory->4GB 1067 DDR3

Posted on Jan 23, 2011 9:01 PM

Reply
378 replies

Oct 3, 2012 2:31 AM in response to bullitt83

Im sorry to hear it friend. Even the method I posted doesnt work for me every time, I gotta run the silly repair permissions a few times.


When you run repair permissions, does it fix stuff in the display prefs? Perhaps try getting another adapter that is recommended on here, I have tried moshi and a neet adapter and both give me headaches. Although before the infamous 'update' I had no problems connectin to my samsung monitor with the moshi.

Oct 3, 2012 2:32 AM in response to bullitt83

Hi there,


You should take a look into the instructions I posted here: https://discussions.apple.com/thread/2731536?answerId=18028302022#18028302022


These instructions were for Lion, but maybe this is still a problem on Mondain Lion... Basically the problem has to do with the Integrated/Discrete modes of the graphical card. Once I found the solution I never (ever) had problems on detecting any external display (with dvi, vga, hdmi). Take a look, hope it helps!


Cheers!

Oct 3, 2012 8:28 AM in response to Vic-zx

What macbook pro do you have?

The solution I took only works for Macbooks with "discrete cards" (ATI or Nvidia). They also have "Intel integrated graphics" card, which was giving me problems. Basically when in the graphical card is in the "integrated" mode it does not output video signal... Not sure if this problem only took place on Lion...


My macbook is Macbook Pro 15, early 2011, with ATI graphics card... If you have only "Intel integrated graphics card", the solution I propose will probably not work (as it basically only makes sure the "discrete" graphics mode is selected)...


Good luck! Cheers!

Oct 3, 2012 8:44 AM in response to Vic-zx

hmmm... that is very strange. It is a configuration very similar to mine (with the ATI card). I also use Samsung Syncmaster (do not remember which model).


Did you make sure that you put the "Discrete Only" mode on the gxfCardStatus when you plug your external display? For me it does not matter if I put it before, or after I plug... once I set it (so ATI working), the external display gets recognized immediatelly! If you do not do that, it will probably use the "discrete" by default (it consumes less power)... This happens even more if you do not have your macbook plugged to the power. Do play with the modes on gfxCardStatus (also check for the latest version)... You need to make sure that whenever you are connected it needs to be "Discrete only"!


Indeed... not sure how this problem keeps poping up after so much time being reported! Apple should solve it...

Oct 3, 2012 8:48 AM in response to emgsilva

It was that stupid thunderbolt update in june that wrecked everything. Until then I had no problems with my samsung, but since then I have have to go through this long process to even have a hope of getting the mac to recognize it. I bought a new adapter and still the same problem. Tried gfx but doesnt work for me. I dont think this will be fixed for a long time as it has plagued mac users for years and apple are being sloppy about it.

Oct 3, 2012 9:01 AM in response to Vic-zx

Just a final try 😝


Did you ever tried the SMC reset? I did that some time ago... not sure if before I discovered the gfxCardStatus solution... I remember some people referring to use that solution to solve problems connecting with external displays. It does not hurt to try, I do not think there are any problems, I did not have any. For instructions go here: http://support.apple.com/kb/HT3964


Actually there refer that the SMC reset is used to solve some "video problems" (although they refer iMacs)... but, who knows.


Cheers!

my macbook pro does not detect external display anymore

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