Ok, everyone I have the Dichro DG-1 color head 400 watt. It has the color dials on the front. The bulbs say Osram EUL 200 watt 24 volt. Both of them are in great condition. The head plugs into a voltage regulator? It is a heavy rectangular box about 3 1/2 x5x7. When I plug it in i can hear it working. Must be a wiring issue or something? This is not my specialty so I guess I have nothing to loose by taking it apart when time allows. Any other ideas are appreciated.