a question about metal halide bulbs
 

so christmas was good to me, got a used pair of ballasts and bulbs for my fishtank.

everything wired up easily, and the switch was thrown. both bulbs began to warm up and i was feelin pretty proud of myself.

after a few mins one of the bulbs began to flicker, almost strobelike, then after a few mins of the flicker it went out only to warm up again in a few more mins and restart the process. i turned off the setup, let cool and switched bulbs, and the same bulb (other socket) again flickered.
i was told the bulbs were only used about half a year, could it just be from not being used for over a year? or is the bulb dead?

anyone else have this happen before? any comments would be really apreciated

How long did you let it flicker for before you turned it off? I've seen some that like to flicker for a few minutes while they warm up. Personally, I wouldn't keep one on my tank that flickered. I'd just replace it.

Sounds like you bought ballasts from the same guy another Canreefer did. This guy paid a fair buck for supposedly 3 month old (than turned to 6 month old) ballasts that worked 4 hours before crapping out.

He said the bulb flickered from both ballasts. From what I understood anyway... lol!

Sounds like there was some flickering on these before dying completely. Everything is potted so assume no connectors loosened, but then the potting makes it near impossible to repair.

Brighteyes, all I can suggest is the same I said to the other guy, check to see if anything shook itself apart in shipping. If everything looks good, troubleshoot and hopefully a cheap replacement part gets you going again.

Make sure you unplug, and let them sit for a while. If they are not electroic ballasts, there will be a capacitor in them, that cap will hold a massive charge for a while after they are unplugged.

Sounds sort of like what happens when you use a pulse-start lamp on a probe-start ballast. Do you see any markings on the ballast? If it says M57 then it's a probe-start. If it says M137 or M135 then it's a pulse-start ... odds are *pretty good* though that you have a probe-start ballast.

Another way to tell, probe-start ballasts are a transformer and a capacitor (2 things), pulse-starts are a transformer, capacitor, and an ignitor (3 things). Ignitors and capacitors look similar - usually aluminium - the ignitors might be a bit smaller.

What about the lamps, do you know what brand they are? There's a fair mix of lamps on the market, both pulse-start and probe-start lamps.

Anyhow, without knowing anything more about the setup, that's my guess. If it is a probe-start ballast and pulse-start lamp, it's not the end of the world, they can take up to 20-30 minutes to fire up and stay solidly lit. Usually it gets better after several days worth of use though.

Thing to do though is, when you go to buy new lamps, make sure you order lamps that match the type of ballast you've got. Most vendors will tell you what ballast is needed for the lamps. For example, take a look at this page:
http://www.jlaquatics.com/phpstore/s...t_ID=lb-h1715i

In red text at the bottom of the description it says "this lamp requires a probe-start ballast or electronic ballast." And on this one:
http://www.jlaquatics.com/phpstore/s...ct_ID=lb-h1710
... it says to use a pulse-start.

Hope this helps! :)

What ballasts are you using?

I know you said that you changed the bulb to the other ballast. How long did you run them on each ballast?

Sounds exactly like what happens to core & coil ballasts when they go bad. If they are electronic then I would get new bulbs, if that doesn't work contact the (electronic) balasts manufacturer and they should be able to figure it out.

I agree with Delphinus

I had the same problem with my ML

Sounds sort of like what happens when you use a pulse-start lamp on a probe-start ballast. Do you see any markings on the ballast? If it says M57 then it's a probe-start. If it says M137 or M135 then it's a pulse-start ... odds are *pretty good* though that you have a probe-start ballast

Check your ballast and lights for compatibility.

J&L show the type of ballast required with each of their lights.

Tom R

thanks for all the feedback!!

the ballasts are standard probe start. i wired both myself and feel comfortable with the connections (first year electrician.) both work wonderfully. i have had the good bulb in both for an hour plus to make sure.

thats an interesting point about the pulse start bulb idea... i never let the bulb cycle thru more than twice... hmm...
if it werent for the fact both are wired into my system now, i'd test the theory about letting it warm for more than 15 mins. both apear to be venture (good ones a 10k, bad ones a 14k), and so are the ballasts.

i do however think maybe the bulb is just worn out, and ready to be retired. the arc tube is pretty blackened.