Does a bad ballast keep the bulb lit?

How's this for a find: I picked up a 400w HPS ballast in a thrift store for $6, and danced back to the car. Before I invested in a bulb (this is my first grow in a decade, and I gave away all my stuff many years ago), I took it in to the local store and had them test it. They said it was good.
I fired it up with a brand new bulb yesterday, and it lit right up. It is running now, too (the second day). But it seems to me like it ought to be producing a heck of a lot more heat than it is. I've got a lensed, vented reflector, but with the vent fan off, I can touch the reflector's top or glass without any discomfort. I've can't tell if it not bright as it should be, because I've got nothing to compare it to.
Do ballasts ever die gradually? Am I just being paranoid?
Thanks for any tips!

Yes, they can wear out. Yet, a 400 watt bulb HPS setup is warm but not hot if you know what I mean.

I take it this is a wire wound ballast and not an electronic ballast?

For comparison, I will say that my 400 watt HPS electronic ballast setup+bulb is as warm or cooler than my wirewound 250 Watt MH bulb setup. Much higher efficiency.

A 400 watt HPS shouldnt put off a lot of heat. It sounds normal to me. It should be warm to the touch but not so hot that its uncomfortable.

Great! Thanks guys/you rule!
Just for clarity (should anyone else or you two have more input), I've got a 400w conversion MH bulb in a reflector that can handle up to 1000w, and the ballast is wire wound (not digital).

stevenr said:

Great! Thanks guys/you rule!
Just for clarity (should anyone else or you two have more input), I've got a 400w conversion MH bulb in a reflactor that can handle up to 1000w, and the ballast is wire-wound (not digital).

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my 400 watt hps that i got does not put off much heat good find i give 50 for mine with hood and 4 bulbs its a sun beam