computer recognizes projector, but projector doesn't recognize computer

Question

computer recognizes projector, but projector doesn't recognize computer

Hi!

I am trying to connect a video projector to my new MacBook Pro (specs see below). I have tried with two different projectors and failed. Both projectors used a VGA cable, which I connected with Apple's DVI-to-VGA adapter (bought with my previous 2006 MacBook Pro), which I then connected with a third party (LogiLink) Mini DP-to-DVI-I adapter, which I connected with the MacBook Pro.

The projectors DO show up in the "Monitors"-menu, so they are recognized by my computer. The MacBook Pro also immediately went into sync mode and adjusted its screen resolution to that of the projector. However, both monitors only displayed their blue screen "searching for input" message, so both didn't recognize any signal coming from the computer. When connected to a Wintel laptop, both recognized it immediately, and displayed its mirrored image. Connecting back to my MacBook Pro, again only the blue "searching for signal" screen. Even putting the MacBook Pro to sleep and waking it up didn't resolve the problem.

I am at loss to what is the reason. From my 2006 first generation MacBook Pro I am used to plug&play when it comes to projectors. No restart, no keypress needed on the computer. Has that changed somehow with the newest generation? (I am also missing the F7 monitor switch key, but that's a different matter, isn't it?)

I have activated the firewall and the stealth mode. Can this play a role? I wouldn't think so, however.

Help very much appreciated.

McBook Pro Core i5, 15'', 2.4 GHz, 4GB, Mac OS X (10.6.5), NVIDIA GeForce GT 330M

Posted on Dec 6, 2010 9:53 AM

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Answer 1

Top-ranking reply

TheShortStory

Level 1

8 points

Mar 19, 2011 5:47 AM in response to Martin Schmitz-Bethge

I have a similar problem as well. my 13" 2011 mb pro recognizes my external display (connected via mini-display to hdmi adapter) but the display doesn't recognize the input signal. On my windows partition, though, it works perfectly....!

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Answer 2

May 17, 2011 7:42 PM in response to Martin Schmitz-Bethge

This is what I have found out: Your base resolution of your MBP is too high and it is sending too high a resolution to the projector, hence the dead projector. Instead, lower the MBP resolution to something like 1024x768. Hit mirroring. Try the input of the projector. If that doesn't work, you need to change the resolution of the projector. Turn off mirroring. Hit the button "GATHER WINDOWS." You should then have the projector's window behind the laptop's window. Click on that and I bet the resolution in that window is set too high. Reset that resolution so that both match and voila! Your projector will start working. Then go ahead and set the color settings for that projector and name it, so the computer will remember the projector in the future. Also, when anyone has a presentation, go in many minutes before and try this out with a "strange" projector.

My MBP has a high resolution screen and tends to send a very high resolution signal to other devices.

The problem is that the window for the other monitor is been default set too high and you have to adjust it separately, even though mirroring is supposedly turned on. I thought I was going to have to get rid of my computer or go back to my old one, but this indeed worked. DVI input projectors tend to have a higher resolution, 1280 or even 1400 and you may find that a later MBP will work more readily with those projectors that have DVI inputs, but most projectors that are around these days are VGA style projectors and have a much lower resolution. Hope this helps.

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Answer 3

lamboona

Level 1

0 points

Mar 17, 2011 7:23 AM in response to Martin Schmitz-Bethge

I too recently tried to connect my MBP to 2 different projectors using mini display port to vga and nothing - almost ruined my best mans speech at a wedding 3 weeks ago. I also have the same problem trying to connect MBP to TV via an HDMI adapter. Really disappointed as everything else Apple just seems to work. Clearly this is a major problem, and many users are suffering from this problem - Apple need to sort it out quick time!!

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Answer 4

jzack52

Level 1

8 points

Dec 8, 2010 11:21 AM in response to Martin Schmitz-Bethge

Martin,
I am having similar problems with my new MacBookPro. My previous MacBookPro was plug and play with a video projector after setting Display preferences to "mirror display." My new MacBookPro connected to the video projector with a mini display to VGA connector recognizes the projector and goes to 1024 x 768 resolution. My computer desktop display has with NO ICONS or anything else on the screen. I tried setting the DISPLAY preferences in System Prefs and clicked on Gather Windows and Detect Displays but the projector will not display my desktop, only a blank desktop with no icons. When I switch the mini-display to VGA connector to a 13" Mac laptop everything displays just fine. So it is something with my MacBookPro or my procedure with it. Is there a preferred procedure or sequence for starting the computer/projector and making the VGA connection to the projector?

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Answer 5

Jedwards

Level 1

4 points

Jan 21, 2011 4:06 AM in response to jzack52

I have had exactly the same problem yesterday with my Macbook Pro with a projector at a school where I was doing an assembly. My Macbook recognised the projector, displaying the resolutions on the Display preferences, but the projector did not display anything, just said "No Signal". I had previously used an old Macbook which worked fine with that projector.

My Macbook Pro does work with other projectors but since updating to Mac OS X 10.6.6 I now have to restart my laptop to get it to sync with the projectors. I used to be able to just connect the lead and it would sync straight away without having to restart, so I wonder if there is a problem with the Mac OS X 10.6.6.update

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Answer 6

Aug 4, 2012 1:36 PM in response to Martin Schmitz-Bethge

The same problem with my newest mid-2012 MacBook Pro 13 inch, 2.9 GHz Intel Core i7 running Lion 10.7.4.

It has suddently stopped recognizing projectors after 2 weeks since I've bought it. After a day of troubleshooting, I have verified that the VGA video cable and Apple's MiniDisplay Port to VGA adapter were working. And then suddenly everything seemed to be back to normal - and I could connect it again to a projector. But the following day connected MacBook Pro to projector and all I could get was again the black screen with flickering thin vertical whitish lines. I always use extended desktop with the projector.

More troubleshooting... At the end WHAT SOLVED my problem:

(1) Started my MacBook Pro into safe boot:

http://support.apple.com/kb/HT1564

(2) You may want to try doing this with projector connected or disconnected. Got extended desktop through the projector.

(3) Disconnected MBP from the projector. Restarted MBP as usual (NOT safe boot). So far, after a week of use (and no restarts) MBP was connecting properly to 4 projectors.

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Answer 7

Wutzel

Level 1

0 points

Jan 21, 2011 12:48 PM in response to Martin Schmitz-Bethge

I have a similar problem and had this already several times on job interviews... when I try to connect my MBP via an minidvi(or whatever) and VGA-adapter to the beamer, the beamer does not get an input signal although the MBP is trying - at least the monitor flickers once. When I use the same adapter to plug a second monitor this problem does not occur and everything works as it should. If anybody has a solution on this... I would be very grateful.

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Answer 8

Feb 2, 2011 5:23 PM in response to Wutzel

Same problem...but it only started after I added a separate log-in account. The restart works for me because somehow the system isn't confounded by two login spaces. Even when I'm signed out of the other account it still requires a re-start to start working on the projector. Do you have more than one account on your system?

Is there any fix for this that doesn't require a restart???

I can't remove the second account but wonder if this may be a bit more of a hint about why this is happening and could help somebody find a work-around.

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Answer 9

Feb 9, 2011 9:20 PM in response to jzack52

I am having the same problem with my year old MacBook Pro. The computer recognizes the projector but the projector screen is blue and searches for the source. The same projector works fine on a Microsoft Windows machine. Any solutions?

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Answer 10

rhinoab

Level 1

0 points

Feb 10, 2011 4:07 AM in response to Martin Schmitz-Bethge

This has started happening to me. Sometimes it works, then sometimes it doesn't. Only seems to affect my macbook pro, older macbook does not have a problem. Restarting sometimes works, but no always. This problem started around 3 weeks ago but has now become more acute. I plug in and out of the projector around 10 times a day so need to know it is a stable connection.

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Answer 11

Feb 12, 2011 12:44 AM in response to Mac_Brian

I stumbled across a solution. When the screen was locked in search mode and the screen was showing only a blue background, I unplugged the DVI mini port adaptor from the computer, waited a minute and plugged it back in. It worked! I could see the computer monitor in the screen. A simple solution.

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Answer 12

RobinLA

Level 1

0 points

Mar 9, 2011 10:15 PM in response to Martin Schmitz-Bethge

Similar problems. I am trying to use a Dell 2100MP projector with any one of my computers iMac, MacBook Pro and MacBook, but all get the same dialog screen on the computer "can't identify this keyboard" and the projector keeps searching for a source.
Got nowhere with online help from Dell.
My guess is that OSX is the culprit since the projector worked with OS9,
Is there a driver for the Mac side that might make it recognize the projector?
Any advice would be appreciated.

Message was edited by: RobinLA

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Answer 13

mgrindel

Level 1

0 points

Mar 16, 2011 2:16 AM in response to Martin Schmitz-Bethge

I do many many presentation at a variety of prospective customer sites.
As a result I need to connect to the video projectors available in the conference room. With my latest macbook pro 15" I seem to have more and more places that I simply can not present at.
The PC's in the room have no problem but the MBP simply does not pickup the video projector.
I'm at the point now where I stand the chance of not being able to present and thus loose the business.
Looks Like I will have to go to a PC if this can not be resolved.....

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Answer 14

J Beau

Level 1

9 points

Mar 16, 2011 1:50 PM in response to Jedwards

I had a similar problem, and here's what it was. When I plugged the VGA to mini display into the computer first, and then connected the VGA to the adapter, the same thing happened to me as happened to you-- a little blip and then no connection. However, if I first plug the VGA into the adapter, and THEN plug the adapter into the mini-display port (in my case a Thunderbolt), then everything works fine. Ridiculous but true. -JB

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Answer 15

GParadee

Level 1

0 points

Mar 23, 2011 4:29 PM in response to TheShortStory

I have the exact same problem with my MBP. Apparently it is a known issue with the models and can not be fixed. The best fix I have is to restart with the projector already connected to the MBP and it will boot with the projector detected and working.

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