Mini DisplayPort to DVI to VGA doesn't work (why?!)

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Mini DisplayPort to DVI to VGA doesn't work (why?!)

I purchased a Mini DisplayPort to DVI adaptor from eBay. It works just fine when connected to a DVI cable to a monitor, but there's no signal when I put a DVI to VGA adapter in-between to connect it to a VGA only display. I was hoping to use a single Mini DisplayPort cable to handle both DVI and VGA connections - am I missing something here?

Here's an image of the connection path: http://img690.imageshack.us/img690/313/photors.jpg

Thanks

Posted on Nov 28, 2009 5:13 AM

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Answer 1

eww

Level 9

53,028 points

Nov 28, 2009 7:21 AM in response to N.Cauldwell

Yes. What you are missing is the mini-Displayport-to-VGA adapter that you need.

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Answer 2

N.Cauldwell Author

Level 1

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Nov 29, 2009 2:04 AM in response to eww

Thanks. Someone on Twitter mentioned the Mini DisplayPort to DVI output is DVI-D only, which means the VGA adapter wouldn't receive an analogue signal to convert to VGA.

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Answer 3

Travis A.

Level 6

14,985 points

Nov 30, 2009 9:31 AM in response to N.Cauldwell

Someone on Twitter mentioned the Mini DisplayPort to DVI output is DVI-D only, which means the VGA adapter wouldn't receive an analogue signal to convert to VGA.

Exactly correct. When you plug a DVI adaptor into mDP the port only sends out the digital signal. Likewise, when you plug a VGA adaptor into mDP the port sends only the analog signal. So using two adaptors in tandem is not possible. You need a separate adaptor for DVI and for VGA, unfortunately.

--Travis

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