Problem with connecting two projectors with iMac

[forty31]

I don't know much about HDCP, but there are a couple of other options you could consider. Instead of the dvi splitter have you consider buying a Matrox dual head2go? It should do what you want and is supported by ProPresenter. Another option is the get a USB to DVI adapter and use the stage display feature built into PP.

[turbo911]

Originally Posted by forty31

I don't know much about HDCP, but there are a couple of other options you could consider. Instead of the dvi splitter have you consider buying a Matrox dual head2go? It should do what you want and is supported by ProPresenter. Another option is the get a USB to DVI adapter and use the stage display feature built into PP.

Matrox Dualhead2go is not what we need. It makes the main screen wider but we need to extend/split the screen so it shows the same image on both but not mirrored with the second one.

I tried today to connect projector with 8ft cable and it wasn't the length of the cable. Basically it is either with iMac like display port doesn't support dual output and not enough power or problem with converter from mini display port to dvi thinking it doesn't support dual display and doesn't have enough power.

So only option is to buy secondary converter USB2DVI and have both projectors connected separately though I am not sure how that will work out and if I will have the same output picture.

Other than that, I have no idea what to do, unless to try that adapter from apple for $100 that says supports dual display and has usb and mini display port along into dvi.

[six5tring]

just a quick side note to say that unless it's changed dual/triple head dvi/vga do not support HDCP

... continuing... man this is an annoying problem isn't it! just quickly... why are you running at 1080p? Given the resolutions of the projector panels I would run at 1280x768 or 720p.

On with the show:

Although both of your projectors officially support HDCP I think that one of them doesn't. After a good read here.. http://www.serialdigital.com/2010/02...nto-switchers/

I think that mac is doing the following.

According to the article HDCP on iMac will be enabled if the first device it see's is HDCP compliant and disable is it's not.

What's happening is:

1) Using your passive splitter you then connect your Optoma projector
2) It does NOT seem to be HDCP compliant, HDCP is turned off.
3) Connect NEC, HDCP is already off so all works.

Using your new HDCP active splitter it is first in line and so the iMac turns HDCP on and the Optoma no longer works.

Please read the article for some possible solutions.

Ben

[forty31]

Originally Posted by turbo911

Matrox Dualhead2go is not what we need. It makes the main screen wider but we need to extend/split the screen so it shows the same image on both but not mirrored with the second one.

I have the triple head so maybe it's different, but when i run pro presenter from it I have the option to tile the screens, putting the same image on all the screens.

It sounds like your best bet may be the adapter from apple, you can always return it if it doesn't work.

[zactommo]

Originally Posted by turbo911

I tried today to connect projector with 8ft cable and it wasn't the length of the cable. Basically it is either with iMac like display port doesn't support dual output and not enough power or problem with converter from mini display port to dvi thinking it doesn't support dual display and doesn't have enough power

The mac display port output isn't a dual output. Its a single output that can be set to either mirror your desktop, or extended desktop, which is what you are trying to do.

What you want is a single output from the iMac split two ways. Using a passive y type splitter like you currently are using isn't the best way to do it.

I think the problem you are running into is this. The splitter that you are using most likely doesn't pass all data to both of the projectors. Most passive splitters are like this, because the can only pass data onwards. Whether a display adaptor will work with not all pins connector varies model to model. Macs tend to be fussyer than PCs about this. I've had a similar situation with a VGA cable. A couple of pins were out in the cable, but all the main video signal pins were there. The cable would work with some computers, not with others, depending on the video card. It wouldn't work with the iMac I used to have.

If you get an active splitter, the computer sees only 1 output device, with all the correct data, then it makes sure the appropriate data is sent to each output. The passive splitter usually sends all the main video data correctly, but the auxiliary data, such as what allows the computer to tell what sort of display its connected to, native resolution of the display etc, gets stuffed up, and you get strange things happening like your getting currently.

[turbo911]

Hello,

Thank you everyone for the help that you have provided. It appears to be the adapters that I have tried didn't support DVI-D Dual Link.

I went ahead and bought DVI-D Dual Link adapter from apple for $100 and it works flawlessly and both projectors work fine. One is connected with 25ft cable and other is 2x50ft DVI-D Dual Link cables. Looks like iMacs do support 2 more external screens, just need to get the right cable and plus it needed more power.

Thanks again for help and I am relieved now after solving everything and making it work.

[EricE]

Originally Posted by turbo911

I can't return it because I already bought propresenter and other software for it.

Get a USB video adapter and use Stage Display on that rear screen. No splitter needed if you do that

[EricE]

Also DVI is one of the hardest things to push long distance - you could go DVI to HDMI (or straight from mini-displayport to HDMI) and then use something like this: http://www.networktechinc.com/hdmi-splitter.html If your projectors are recent, I'd wager they have HDMI too.

Nice thing about the Network Technologies boxes is the extenders are built in to the splitter - it makes a very clean solution.

[northcrestmedia]

We are having problems with the imac overheating and burning up display dongles I think we are sore having lag in our pro presenter this is a stock machine off the shelf I think were going to switch to pc to a 4 core 16 gigs of ram and a graphics card that supports 4 outputs mac just on the way they use to be and they are expensive I can build a pc less than a new mac.

[northcrestmedia]

Originally Posted by turbo911

Hello,

Thank you everyone for the help that you have provided. It appears to be the adapters that I have tried didn't support DVI-D Dual Link.

I went ahead and bought DVI-D Dual Link adapter from apple for $100 and it works flawlessly and both projectors work fine. One is connected with 25ft cable and other is 2x50ft DVI-D Dual Link cables. Looks like iMacs do support 2 more external screens, just need to get the right cable and plus it needed more power.

Thanks again for help and I am relieved now after solving everything and making it work.

Is this an IMAC?