Help with Nano-Cube Light

[64physhy]

The light on my 28G Nano Cube HQI keeps shutting off then coming back on. I replaced the bulb and the ballast, but it keeps doing it. I also checked the fans, and all 4 are working. I have 2 fans pushing and 2 pulling for flow over the bulb. Any ideas what could be causing it? Thanks
Dave

[bpro32]

are you using a gfi?

[afitzwater]

where are you located? maybe someone can come land a hand

[64physhy]

It's not plugged into a GFI. It was fine until I replaced the bulb (because it was old), then the ballast died, was doing this for a while, then went off all together, so I got a new ballast, and it keeps shutting off and on. I'm in Escondido. I might see if Chris (Lotsafishies) has any ideas.

[64physhy]

Well, Chris was here and doesn't know. Thinks possibly overheating. Doesn't seem like it should be overheating. It did during the hottest part of summer, but with it being a lot cooler in the house now, it doesn't seem like it should be. I have the ballast sitting on spacers made of hose to get air circulation around it. ANy ideas?

[LotsaFishies]

Just some more info: only the light is flicking off / on, everything else remains on, unaffected.

The light is shutting off after being on for ~10-20 minutes...

[64physhy]

I put a fan in the cabinet. I'll see if it keeps it up tomorrow.

[64physhy]

morning bump

[619andyp]

It really sounds like over heating. The JBJ HQIs have a feature that protects the canopy from catching fire. If the light gets too hot, it automatically turns off. When the canopy has cooled, it automatically turns back on. Since it is turning off after being on for ten or twenty minutes, then automatically turns back on again, this is probably the case. I know you said the fans still work but I would think they might need to be replaced anyways. Also, you could call JBJ and have them trouble shoot with you. I have called them before and they were willing to help with all my questions.

[64physhy]

The fan blowing on the ballast did no good. I'll check out the fixture. I'll try calling JBJ tomorrow.

[ajn81]

I had this problem before with one of my HQI lights, it would turn itself off every 15 minutes or so. I replaced the bulb and never again had the problem.

**The bulb that was causing the problem was only about a month old, so I'm guessing there was something wrong with it.

[vinny73]

Have you checked the terminals where the bulb fits in? If you lose contact for just a milisecond, the light will not come back on for a period of time. It's a built in safeguard. Obviously a pita but I would check there. The connections are copper. I would check for continuity of your wires from the bulb terminals to the ballast. Like I said, if you lose contact for a split second, it will shut off. If you have a weak connection, the wires will heat up and expand. If you have stranded wire, and only 1 wire is touching, it heats up and expands, it will break the connection until it cools and goes back into place. Also check to make sure the bulb is getting a tight fit in the terminals. HTH, Vinny

[vinny73]

I had this problem before with one of my HQI lights, it would turn itself off every 15 minutes or so. I replaced the bulb and never again had the problem.

**The bulb that was causing the problem was only about a month old, so I'm guessing there was something wrong with it.

Now there's a great idea! Try your old bulb if you still have it. You could very easily got a crappy bulb!

[64physhy]

I had this problem before with one of my HQI lights, it would turn itself off every 15 minutes or so. I replaced the bulb and never again had the problem.

**The bulb that was causing the problem was only about a month old, so I'm guessing there was something wrong with it.

Hope it's not the bulb. This all started when I put a new bulb in.

[64physhy]

Threw the old bulb away already. I took the bulb out and blew the hood out with an air compressor. A lot of crap came out from under the reflector shield and from all the crevices. The new bulb is much more intense than the old one (the old one was about a year and a half old, which is why I changed it). I'm thinking (hoping) that the new intense light is putting off more heat and the crap in there was enough to block airflow just enough to cause the overheat. It's been on for about 20 minutes now without shutting off. Hopefully, it's good.
Is the round thing on the back side of the reflector the thermostat that causes shutdown?