my macbook pro does not detect external display anymore

I tried this many many times. And...it's not NOT working. It "recognizes" the monitor in the system preferences but the monitor itself still states "no signal" but it looks to be going in and out though when it comes to having a signal. The indicator light will go from blue (working) to orange/amber (not working) and "no signal" will flash periodically on the screen. So...we're getting somewhere. I am going to try restarting the computer and also reinstalling Snow Leopard and see if that doesn't do anything.

So I finally got it to work. After a whole mess of times, I finally got the timing right. It was stable. I moved it back to it's regular position and....gone. Just like that.

lol, you'll have to keep doing this every time you want to connect the monitor! did you buy only the cable or is it the cable adapter?

In case some were wondering, I was able to get my monitor and MBP to work together by utilizing a Mini-Display Port to DVI adaptor. I have no idea why the VGA adaptor was not working, but at least my problem is resolved.

Having this same problem. You have any luck?

mine still isn't working tried all... im using a mbpro 2012, mountain lion, mini displayport to hdmi... and as tv a samsung 32"...

tried all settings above.. none works... :-s crappy...

wow, this really *****...When I installed 10.6.8, the external stopped working... I have since tried the MBP 2.3Ghz on various other monitors and they don't wanna play either. And it appears moving up to 10.7 or 10.8 isn't helping either. ***??? It is very dissappointing that there appears to be no fix for this, nor apple offering up any resolutions...

I'm as considering why I would want to take a chance on a newer MBP if there are having the same issues as well.

TM

Hi, i don't where to start... i'm new to here. i got an issue which is really annoying me. i'm now using MBP 13" year 2010 with OS X Ver. 10.8.2. i have a LG Smart TV 47"and need MBP to connect to LG TV with usng Mini-Display Port to HDMI, but very disappointing is i had try many way, it's still show at LG TV 'No Signal" (MBP blue screen blinks), i have try to Press the Option key to enable for "Detect Display' out. Unfortunately, nothing function at all, in the same time i have also try to change the resolution from clicking the scaled with restarted a few times, in the end still No Signal at all. i don't know i still miss out anything or not but so far i tried.....:-(

One thing, i got a Sony Vaio laptop. i had try the sony connected to the same LG TV, and straight away there a signal on the TV. As simple as it for the sony, although have the problem with the resolution doesn't fix exactly to the TV screen, but i have try to change some setting in the TV and problem solved.

I hope someones can help me...

TQVM

I don't understand. This discussion has 15 pages already and Apple is not doing something about it? What's happening? Don't you care about us (your faithfull customers) anymore? Are you people ok with some comments I've seen here like "this is my first and last mac" or "my sony vaio laptop was able to do something my macbook pro coudn't"? Are you really saying to us that you just don't care, and we can go ahead and buy another laptop from the competition so we can solve our issues? We are really upset and waiting an answer from you.

Thanks.

Hi Everyone,

SOLUTION IS HERE:

Buy the "Belkin Mini DisplayPort-to-HDTV Cable" and that's it !

- This cable connects to the MBP minidisplay port then directly to your HDTV/monitor/projector via HDMI. NO converters required. Works perfectly, detects monitor, send signal, mirrows image, extends display etc.

What I have tried before, I also called apple support.

1 - Different MDP to VGA adapter

2 - Different Monitors

3 - Restart with safeboot and VGA cable and monitor connected to MBP via MDP

3 - Reset PRAM. (worked only once then no signal)

Thanks.

My system: MBP 13" Mid 2012 i7 2.9ghz 8 ram intel hd 4000 750gb OS Mountain Lion

I'm also very disappointed by Apple. How come that Mountain Lion creates so many problems with displays, even is they are Apple displays. This is no incident anymore.

Apple, solve this problem asap. I can't do my work on a macbook pro only. I need my cinema screen.

I have Macbook Pro Retina, BenQ monitor. All worked fine until recent update. (10.8.2). Now I can only use external monitor if lid closed on MBpro.

With lid open I get black screens on Pro and External monitor (with large cursor).

What is going on?

I am using 2011 MBP with Thunderbolt and trying to connect Asus PB278Q monitor. After trying various adapters that did not work I bought a "Cable Matters MiniDisplayPort-to-DP" 2m cable from Amazon. Something just doesn't seem right having to use a silly adapter on two high tech devices such as these!

I continued to experience no luck, meaning the external monitor was not being detected. I tried downloading gfxCardStatus to force my MBP into discrete mode etc.

Then as a last-ditch effort I focused on making sure my displayport cable was actually FULLY plugged into the monitor. Sadly enough this was the issue! DisplayPort cables are pretty thick and not very bendy which makes them difficult to maneuver. They usually *snap* into place if you have it plugged in correctly. So folks, please make sure your displayport cable is fully plugged in before you pull your hair out thinking it is a software issue. Don't just reach underneath your monitor at an awkward angle and assume you've got it locked into a connected position.

I realize this won't help that many folks issues here but you never know!

In desperation i thought i would do as you suggested. Disconnected all plugs. Re connected them and tightened screws. At present monitor working again. Unbelievable. Thanks.

Ps i think it is working on only 1 thunderbolt port.

I finally reinstalled Snow Leopard and the screen is still not detected. I think I might swing by Best Buy tonight and pick up a new adapter. I have to use a VGA adapter because it's the only port available on the back of the monitor. I'm not going to buy a whole new monitor just to use an HDMI adapter when this one works fine.