VHO Bulbs don't fire, what could be wrong?

MAG · Joined: 16 Aug 2007 Posts: 8

Hi folks-

Some of you may remember me from about two weeks ago; I had problems
with my MH bulbs popping the GFCI outlet on turn-on. That's all sorted
out. It turns out that replacing the GFCI outlet solved the problem.

Now I've got a different problem, that I noticed when I was working on
the MH issue. Sometime recently, the 2 110W VHO bulbs stopped firing.
I just get a dull orange glow near the ends of the tubes.

Figuring these bulbs were just old, I got new ones from Hamilton
Technology (supplier of the lighting hood), and swapped them out. The
new ones don't light at all, though I get a brief flash when turning off
the power. Tried combinations of old & new bulbs; no difference. The
old ones glow orange, the new ones give nothing.

I checked the connections; all is OK.

The ballast is a standard magnetic variety (not an electronic one), and
I believe it is (supposedly) instant start since there's no obvious
starting capacitor in the circuit.

Sounds to me like the ballast must be bad (it's six years old), but if
anyone can suggest an alternative cause for what I'm seeing, I'd like to
investigate that before plunking down $ for a new ballast.

Marc

Archived from group: rec>aquaria>freshwater>plants

George Pontis · Joined: 16 Aug 2007 Posts: 22

In article ,
somebody@somewhere.com says...
> Hi folks-
>
> Some of you may remember me from about two weeks ago; I had problems
> with my MH bulbs popping the GFCI outlet on turn-on. That's all sorted
> out. It turns out that replacing the GFCI outlet solved the problem.
>
> Now I've got a different problem, that I noticed when I was working on
> the MH issue. Sometime recently, the 2 110W VHO bulbs stopped firing.
> I just get a dull orange glow near the ends of the tubes.
>
> Figuring these bulbs were just old, I got new ones from Hamilton
> Technology (supplier of the lighting hood), and swapped them out. The
> new ones don't light at all, though I get a brief flash when turning off
> the power. Tried combinations of old & new bulbs; no difference. The
> old ones glow orange, the new ones give nothing.
>
> I checked the connections; all is OK.
>
> The ballast is a standard magnetic variety (not an electronic one), and
> I believe it is (supposedly) instant start since there's no obvious
> starting capacitor in the circuit.
>
> Sounds to me like the ballast must be bad (it's six years old), but if
> anyone can suggest an alternative cause for what I'm seeing, I'd like to
> investigate that before plunking down $ for a new ballast.
>
> Marc
>

If the orange glow at the ends of the old lamps was the heater glowing, then you
should see exactly the same thing happening with the new lamps. Is it possible
that you did not install the lamps properly ? Both pins need to make contact so
the heater can be energized. Without the preheat, some ballasts won't have high
enough open-circuit voltage to fire the lamps. Hamilton would probably recognize
the symptoms and have some specific advice if you can reach someone there.

dc · Joined: 16 Aug 2007 Posts: 37

MAG wrote in
@newsgroups.comcast.net:

> Now I've got a different problem, that I noticed when I was working on
> the MH issue. Sometime recently, the 2 110W VHO bulbs stopped firing.
> I just get a dull orange glow near the ends of the tubes.

Sounds a little like what happens to us at work every time we turn the fish
room lights on. Usually touching or rubbing the dull bulbs will coax them
to come on though. Many of our balasts are no doubt pretty old too. Smile