1084 Monitor doesn't work with RGB. Composite works fine

[Antiriad]

Guys

My 1084 Monitor has stopped displaying the Amiga RGB signal. It worked for a day after I removed from storage and the last time I turned it on it didn't. However if I connect an external composite input it works. Could the problem be with the Amiga, the cable or the monitor?

Anybody else had this problem before?

BTW The Amiga comp output is working propely

Thanks

Mike