Are the ones your connecting meant for 120v applications?
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Good thought.
Try using the green grd. terminal. I have one of these things though in my E.R. and it's just the two D.C. wires, no ground, and it works fine. 15" Marinelight.
Are the tubes actually in the holders properly? Sometimes the tube pins do not make contact with the fingers in the holder untill wiggled just right.
Are the wires between ballast and the holders actually in place?
Are the tubes or at least one of them faulty.
The holders could be faulty.
The ballast could be faulty.
I assume you checked that there is voltage at the ballast.
Any hum, not a guarantee that the ballast works since some of them are dead quiet.
A last test would be use the voltmeter and put the probes in the tube holders and turn the unit on. One probe in holder of one of the tubes at each end.
BE CAREFULL.
i know the 120V units, rapid starts, produce upwards of 350v to start the tubes and once the tube lights that voltage drops to ~ 60V. I have never tested my little 12V unit but I suspect the startup voltage would be similar so be carefull or you could get one heck of a blast.
If you don't see something like that then I would suspect a faulty ballast, new or not.
Just a last warning about flourescents in case someone thinks 350V is ok, Some types of flourescent tubes use upwards of 750V which can give a real blast and ruin your meter. So if you try this at the shop/home be very carefull.
The INSTANT START types are the higher voltage.
