I did as you said and moved the connection to high. I have not got a pc to test it on yet but tried to hook up my laptop with extended desktop running and set the resolution to 640x480 and 800x600 and nothing happened. Then I tried 1024x768 and got a picture that was out of sync (lines accross screen but could make out windows desktop under it) but at least I know the monitor is working!
I did notice the picture was a little darker in the corner but know thats something to do with degaussing?