Imac 2009 does NOT detect external apple display

Hello,

I have an iMac (2009 3.06 ghz intel core 2 duo) and a apple 20" external display (1st version, not the new LED ones).

I use a mini.dvi to dvi adapter to connect them.

The "on" light on the external display is on but the screen is black.

On my iMac, no display is detected at all, after reset, sleep, fn f3, unplug & plug, nothing (in preferences also).

It just does not detect the external display.

The external display worked before with a Mac Mini, perfectly.

Please help, Thank you.

G'day and welcome to the forums.

Worked well on the Mini ~ are you using the same connections or is the mini DVI new and by the 1st version, do you mean an ADC (Apple Direct Connection)

I have this one:
http://static.pcinpact.com/images/bd/news/44424-cinema-display-lcd-apple.jpg

SORRY its not mini dvi, its mini display port!! (mini display port to dvi adaptor)

and yes, the mini display port adapter is new, the dvi coming out of the display looks built-in

should i try a dual link adaptor ?

thanks

Make sure your connecting cable is DVI-D not DVI-I

I had this problem where my iMac 27 suddenly stopped detecting the external display (Dell 2007) having done so happily for 6 months. Happened at the time of update to 10.6.6, which may or may not be significant.
I was also using a mini display port to DVI adapter. Switching to a DVI-D cable cured the problem. You have a DVI-D cable if ALL the little pins are there - no gap in the middle.