What the hell is wrong with my light?

I have a 400w MH. I just tried to turn it on, but as soon as the bulb warms up and achieves it's full brightness, it goes off and my ballast makes a funny buzzing sound.

The bulb is new (about 3 weeks old).
The ballast is old, but I think I used it twice years ago. Certainly shouldn't be worn out yet.
It's been off for the last 6 hours, so it isn't overheated.

Anybody had this problem?

Sounds like your ballast is on the fritz. Check all the wiring and maybe try another new bulb.

I still have this problem. It lights upto full brightness, then it shuts off, but the ballast is still on because I can hear it buzzing. I also put a sodium bulb into the ballast to see if it would work and it did. So it seems as if the problem is with my bulb.

I've only been using the bulb for a few weeks, but it has black in or around the inner bulb of my MH. I've never used a MH bulb before so I don't know if this is supposed to happen or if it's burnt out.

Anybody have any experience with burnt out bulbs?
Bear in mind that the bulb DOES come on at first and then shuts off. Would it do that if it was burnt out?

the bulb could have a weak filiment and when it heats up just a little it expands and loses its connection

jar87 said:

the bulb could have a weak filiment and when it heats up just a little it expands and loses its connection

Click to expand...

The thing is - if there is something wrong with it then I plan on sending it back, but in order to do that I need to be sure that there is something wrong with it.

Obviously there is since you sodium bulb worked.

Doesn't matter. They won't accept it back anyway, according to their return policy.

For those that are interested, this is the bulb:

http://cgi.ebay.co.uk/400-watt-MH-SOLARBURST-HYDRO-growlamp-light-bulb_W0QQitemZ140280680435QQcmdZViewItemQQptZUK_Light_Bulbs?hash=item20a9614ff3&_trksid=p3286.c0.m14&_trkparms=65%3A12|66%3A2|39%3A1|72%3A1683|293%3A1|294%3A50

you could get a multimeter to test your ballast's output

A ballast has a big capicator that is used to boost the voltage from the transformer. By physical design, they are somewhat like a battery in makeup. If idle for extended time, the cap can go bad. In a normal Ballast, the transformer must be good or it would be smoking and stink like shit. the ignighter must be on or the bulb would not fire. so the cap must be going. Pull it, take it to an electrical supply company and get a new one, it will be cheaper than a grow shop.. BE CAREFUL, EVEN WHEN UNPLUGGED, A CAP CAN GIVE YOU A SHOCK THAT WILL MAKE YOU PISS YOUR PANTS. 1. BE SURE THE BALLAST IS UNPLUGED FROM THE LIGHT AND WALL. 2. MAKE SURE THE BALLAST IS UNPLUGGED FROM THE LIGHT AND WALL. 3. Take a big ass insulated screwdriver and short across the cap leads before you pull it. 4. re-read # 1& 2 before you do anything.

jar87 said:

you could get a multimeter to test your ballast's output

Click to expand...

Unless your a qualified electronics tech I would advise against using a multimeter on a ballast. Look at the size of the cables to the lamp. Look at the size of the leads on the meter, See where we are going here ???