mac pro and projector. dvi works. mini display doesnt?

[nunes013]

At my school I am a student sound/lighting technician. We have a mac pro that has two mini display ports and a dvi port. We use a video switcher that has a dvi in and out that sends the video to our projector. Today we are running a slideshow for our music camp but we have a problem. Our video switcher for some reason doesnt like mini display port. When we send a dvi signal from mac pro>mini display to dvi adaptor>dvi cable>video switcher we dont get a signal. When we send it mac pro dvi out>dvi cable> to video switcher it works. We use the dvi out for our monitor so we are trying to use the mini display for our projector. Also, we used a macbook pro to send the same signal, macbook pro>mini display to dvi adaptor>dvi cable> video switcher and it doesnt see the signal.

so basically, when we use a mini display to dvi adaptor it doesnt get a signal but when we use just a dvi out it works. the computers dont recognize the projector when we use mini display either. any ideas.


EDIT: could this because we need a dual link adaptor.

 

[TheAnalogue]

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Needing a dual link DVI seems the most likely to me

 

[CaptainChunk]

You technically only need the dual-link adapter if you're driving resolutions above 1920x1200 (which is doubtful for most projectors).

But I have seen strange cases where the dual-link adapters work where the single-link ones do not, in similar circumstances. I suppose you could give it a try and see how it works.

 

[nunes013]

our projector is a christie and it is used in a good size concert hall so i wouldnt doubt the resolution might be up there. i am going to check and try it with my friend who is another student tech friday and we will see what happens. will post update.

 

[iBookG4user]

Try an active mini-displayport to DVI adapter like the one here. See if using that fixes things.

 

[nunes013]

the dual link cable worked. we think it worked over the regular adaptor because the dvi cable going to our projector is 60 ft long and the regular adaptor couldn't push the signal that far or something while supporting such a high resolution. anyway thanks!!!!! we just ordered one for $50 new on ebay.