my macbook pro does not detect external display anymore

I have replied a few months ago. My HP 23 LED monitor hooked to my MBP by a Thunderbolt-DVI adaptor does not consistently bootup with the MBP, never has.When it does not, the trick of unplugging the power plug on the monitor, then unplugging the adaptor from the MBP, waiting until the MBP screen flashes blue and resets, then quickly plugging in the monitor (it begins to scan for a signal) and then plugging in the adaptor to the MBP>gets the monitor up and going.

About half the time the monitor boots up on its own, but about half the time I need to use the above work-around.

From the other posts, I still can't believe their are that many funky adaptors and am still prone to believe that this is some SW problem with non-Apple monitors interfacing with the MBP.

I have the same exact problem....Anyone know what it is...I plug in my hdmi (which has always worked forever) and doesn't have a signal..Started happening after last software update....can't wait until a new update that fixes the problem.....I need HELP(and fast)!...When is the new update going to come out? Figure it out apple.

Having the same problem....used to work then stopped with recent update...When will apple make an update that will fix it?

It seems I'm having a similar issue to everyone else. My macbook pro worked perfectly with my samsung tv connected via minidisplay to vga adapter. Now after a few minutes the tv goes into standby and the macbook screen goes blue and is then back in 'single display' mode. If i go into system preferences and click 'detect displays' it finds the external monitor, works fine, then after a few minutes repeats and goes into standby. Does anyone have anymore information on this? It stopped working before any updates were installed so that can't even be an issue..?

Did you change the screen's update frequency? Try setting it back to 60 Hz - it helped with my Samsung.

None of the settings on either the TV nor the MBP had been altered. The refresh rate is still at 75 Hz like it has always been, plus the other three options (60, 70 & 72 Hz) are all greyed out so can't be selected anyway

hey there fancykat

did you ever find a solution for this? thanks!

14.02.2011 15:19

I will jump on the bandwagon here.
My Macbook Pro is only a few months old, as well as my Sony Bravia, hdmi cord, and adapter.

All was working well until last week. The tv gives me the message of "no signal". I tried to "detect display" again in my prefs, but when I click on that option, nothing happens. Nor do I have the option any longer to select "Sony TV" in either the display tab or the sound prefs.

Absolutely nothing has changed in my setup, and this has become a frustrating issue. Any more news on this problem?

I just got the HDMI to MDP adapter in the mail. Unfortunelty I am getting a quick flash of a blue screen and then nothing. The TV says "no signal" and there is no display found in in the display preferences.

I was really hoping for a plug and play solution. It seems from reading other posts this used to work fine but the last update broke this feature. I hope apple fixes this really soon.

This technique gets me a step further then before but still no solution.

Before I applied this I wasn't even getting any options for a external display. MBP didn't even apear to be recognizing there was something plugged into the port.

I now show options for "mirroring" etc.

I have read one tip that has helped my situation a little. Unplug the external display from power and then unplug cable from computer. Then reconnect the cable to computer with external display but don't plug in the external dispay to the power outlet. This tip has allowed my macbook (brand new latest version) to have active external display settings in systems>displays. Before I did this it would not show any indication on MB that there was an external display connected. This sequence works everytime up to this step. But...

My problem comes when I plug in the external display (32" Vizio 1080p) to the power outlet. The MB screen goes blue (which is usually a good indication) and then the external display shows "no signal". Reconnecting the external display to the power source also causes me to loose all my display settings on the MB putting me back to my original problem...the MB acts like there is no external display at all.

Hi there.

I have the same Problem.

My Setup:

MBP 5,5, 10.6.8; 3rd party MDP-HDMI Adaptor, SyncMaster BX2231 LED as 2nd Display.

It started slowly a few months ago, after sleep mode the Samsung was no longer recognized. Re-plugging of the Adaptor helped, so it was not a big Issue. But last week, replugging did not help anymore! After replugging of the adator, the screen goes blue, but the setup does not change. Even switching off the samsung makes the MBP-Screen turn blue, so it seems, the display gets recognized. Systemprofiler says: No monitor connected.

What i did since then:

connect my MBP to my Bravia-TV via HDMI - worked

plugged my Xbox to my Samsung via HDMI - worked

plugged my MacMini to my Samsung via HDMI - worked

SMC Reset - no change

PRam Reset - no change

Safe boot - no change

all of them with the samsung plugged in and out.

Reinstalled the System - no change

Clean 10.6 Install on external HD - no change

I think I tried every combination to proof, that the single parts are working. But still, my Samsung Display is not recognized by my MBP.

I'm desparate!

.j

This is killing me... I really need to be able to present a Powerpoint Presentation on a large LCD to pitch for a contract and this has totally screwed me. PLEASE FIX THIS NOW!!!!

Well,

I "fixed" it. Got myself a new MBD-HDMI Connector. Everything works fie now, but I just don't understand it. Very strange.

I was having this issue just a few days ago when I switched my graphics card from dicrete to integrated to save battery life. I also installed gfxcardstatus to do this. What I founf from digging around was this from the gfxcardstatus website, "

Why doesn't my external display work?

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 Intel 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."

So after switching back to discrete or dynamioc switching everything was working fine again.

Hope this helps some of you.

Same problem as everyone. Just updated the software and now my external display does not work when connect to my MBP.

Running a MBP on 10.6.8 connected to Dell 27"

Why does apple issue software updates that kills a perfectly working computer .. i thought Windows was bad - but this never happened to any of my windows laptops.. ARGHHHH