Testing an Aqua UV?

My 25 watt Aqua UV stopped working and I'm not sure if it's the bulb or
transformer. The bulb is only 3 months old but the transformer is over 3
years old. I don't have another bulb to test. Anyone know what kind of
voltage (I believe it's AC )that comes out of the transformer? I say I
believe it's AC as the 4 pin bulb connector has 2 green wires and 1 black
and 1 white. When I plug in the transformer it is silent when I put my ear
to it...again, could anyone that has an Aqua 25 watt UV tell me if the
transfomer hums? Any other way to test it? Thanks for any comments!

Bob