what is/was the machine?
they changed things quite a bit...
the monitor should have a "merit type ##" label on it someplace.
if you need a controller (IE you have just the 10 pin right angle connector hanging out of the side of the monitor, wit a green ground wire and a orange/gray power wires, then yes you will need a controller. it's most likely a "white" box.
if you have a box, but it's not responding, check your power connection. it should plug directly to into the small molex plug on a standard ATX power supply what would normally used for a floppy disk drive.