bulb won't fire!!!
 

The bulb ignited yesterday but it took over an hour. Today it's been 4 hours and nothing. The little glass part in the center just glows blue, is this the bulb or my balast? Its a 400 watt mogul run by a magnetic balast, nothing fancy.

Anyone have an old 400 watt mogul bulb i can borrow to test my balast?

I guess the obvious question is, is this a new bulb? Or was it working fine for the longest time and then something happened?

What you describe sounds a little like what happens if you try firing a bulb intended for pulse-start ballast on a probe start. Sometimes it works, sometimes not althouh it seems to improve over time (bulbs must burn in). If that's the case, the obvious solution is to replace the ballast with the correct one, but you may get lucky if you try switching the leads to the lamp around, double checking all connections, tightening that bulb in the socket just a little more, and so on.

But if it was working fine, and then all of a sudden stopped working, then I suspect something else is at fault. Again double check all connections and so on, but it could be you need to replace the lamp or the ballast (or a component).

what ANSI code ballast? and which bulb are you trying to use?

REPLY
 

I'll be doing some testing tonight with the connections etc. I've have this set up running for about 3 months now with no issues. This has only happened this weekend. Do things like this happen as a cause of dust and salt gathering on connections or the bulb?

Just remember that the current going to the bulb is very low, so your connections have to be tight, and the contacts clean. :mrgreen:

Um, I could be wrong, but I'm pretty sure MH use extremely high voltage (low current) to fire, not the other way around.

Danny: double check your grounding of the fixture itself, it doesn't seem like it should make a difference, but for some reason some bulbs just wont fire consistantly/properly if the fixture itself isn't properly grounded.

Andy

Um Is that not exactly what I said in the previous post. :question: :razz:

meh, read it wrong I guess, thought you said low voltage...

reply
 

Well, I found the problem. I took the whole setup to Quick Grow for testing, the balast is ok. When gently unscrewing the bulb it came disconnected from the metal screw in part, whatever its called. So I'm going to get ahold of Aquaria.ca and try to get them to replace it as it is only a couple months old.

In the mean time I was wondering if anyone in Calgary has got a 400 watt mogul socked bulb I can borrow so my corals don't suffer. I haven't got any backup lights.

both wrong and right :mrgreen: a pulse start and HQI use extreamly high voltage and low current, a normal ballast uses normal voltage and high current for the starting then limits the current after the bulb is warmed up.

Steve