MacBook Pro external display not working

[1908]

Hi guys, long time reader first time poster - I hope someone can help me =(

So I went out and bought a new MacBook Pro 15" today in order to replace my aging 2.5 year old macbook (white) – also picked up a new mini displayport to dvi adapter as I had the my old macbook hooked up to my external monitor.

All excited I plug everything in and I cant get the signal from my new 15" to the external monitor as it keeps saying no signal then just goes into sleep. I plug in my old ****** white macbook and low and behold it works again?

Ive gone and got my brothers brand new 13" macbook pro to try as well and it does the same thing as mine?

what could be wrong? Something Im missing here? Help

cheers

 

[spinnerlys]

Maybe that adapter is kaputt, do you have any other mini Display Port to DVI adapter lying around to test the outputs of your MBPs?

What input did you choose to use with the white MB? DVI or VGA?

 

[1908]

nah I havent got any other adapters of this sort lying around, the only other one that I have is the old external adapter that obviously is not around anymore since apple introduced the mini display port.

with the white macbook I used DVI as is the same with this new mini display port.

 

[scaredpoet]

Try this:

With the monitor plugged in, go in your preferences pane, and select "displays."

At the bottom there should be a "Detect Displays" button. Try clicking that and see if your external display comes on.

 

[1908]

Try this:

With the monitor plugged in, go in your preferences pane, and select "displays."

At the bottom there should be a "Detect Displays" button. Try clicking that and see if your external display comes on.

Tried that lol but once I click it nothing happens. When I pull the mini display port plug out of my macbook pro the screen goes blue for a second (macbooks screen)

 

[scaredpoet]

Yeah, that sounds like a bad adapter then.

 

[chopper dave]

Make sure your computer is switching to the discrete graphics chip- if it is stuck on Intel then external displays won't work.

 

[1908]

Make sure your computer is switching to the discrete graphics chip- if it is stuck on Intel then external displays won't work.

How do I do that?

 

[smithrh]

Is your display open or shut?

I've found that unless I have a power plugged into my MacBook, external video output won't work when the display is shut.

 

[1908]

Is your display open or shut?

I've found that unless I have a power plugged into my MacBook, external video output won't work when the display is shut.

tried both with no change - power is plugged in though

 

[tombilske]

go into energy saver and turn off automatic graphics switching. then try plugging it in and see if it works. if it does, then the problem is that it isnt switching to the dedicated graphics card automatically when u plug in the display. if that is the case then go into software update and make sure that you have the latest updates because apple released an update for your computer a just after it was released, that had something to do with the graphics switching. make sure you have that

hope that works for you

 

[1908]

OK guys so I went and exchanged the mini display port adapter on the basis that i thought it was dodgy - turns out this was the problem all along and once I plugged in the new one it worked like a charm!

thanks for everyones contributions =)