VGA to DVI cable to DVI to minidsiplay- not working

[panetta4]

I bought a new computer monitor (a Dell) and the VGA to minidisplay converter wouldn't allow me to split the screen, so I purchased a VGA to DVI cable and then a new minidisplay to DVI adapter.

It is working on my MacBook Pro (I can drag windows off the side of the screen, presumably onto the second screen I am trying to hook up) but not on the Dell computer monitor. Nothing shows up and it says there is no signal coming from my computer. Any idea why or how to fix? Please and thanks.

 

[skorpien]

Somebody correct me if I'm misinformed, but I believe it's to do with digital and analog signals. DVI-D is a purely digital signal whereas DVI-I is a mix of both digital and analog.

Mini DisplayPort to DVI adapter is purely digital (DVI-D).

The DVI to VGA adapter relies on a DVI-I input to be able to provide an analog signal to the VGA device (monitor) as VGA is purely analog.

You would need a Mini DisplayPort to VGA adapter for it to work:

http://store.apple.com/us/product/MB572Z/B/mini-displayport-to-vga-adapter?fnode=51

As to why your computer detects a second screen, it detects a Mini DisplayPort device attached and assumes it's a monitor.