PFO Dual Ballast Problem

[dapettit]

I know it's Christmas day. . .

I have noticed that the light color output on the right side of the tank is much yellower than the left side. I switched the bulbs and it seems to be even yellower. I have not been able to switch the connections to the ballast (hard to get to). I'm running XM 250W mogul base 10K bulbs which are know for being bright white. Does this sound like a ballast problem?

:help:

Dave-

[kcress]

Nope sounds like a bulb problem.
I'm not clear with your abbreviation. PFO.

Metal Halides will start having all sorts of strange spectra coming out of them near end of life. I light my living room with a 175MH and when they get old you can have instant color shifts from white to yellow, or green, or pink... All sorts of stuff. Often it will clear up after a bit but you maybe should consider new bulbs.

Changing the bulbs around can cause them to also change radically because they've been burning in the same position and the metal vapors slowly plate out with gravity playing a part. Move the bulb and now the plated stuff might start coming out into the arc again. But it will be in the wrong proportions.

[dapettit]

I would agree with that, but the bulbs have been fired fot less than 80 hours.

[kcress]

Ah! Don't sweat it.
In the first 100hrs they sometimes wander a bunch too.
If after 100 hrs you still have the problem then you may indeed have a faulty bulb.

Any improvement since your original post?

[dapettit]

No, I switched the light connections to their opposite inputs on the ballast and the left side is still is really yellow. I have them hooked up to an RK2 controller. I will be unplugging the ballast from the RK2 and hooking them up directly to a wall socket.

The weird thing is after switching the inputs the left side still is yellow. I originally had to mode the mogul bases to fit the Luminbright reflector mogul mount. Could that be the problem? Oh, and I also switched the left bulb to the right side and visa-versa and the left side was still yellow. I did that before posting.

[dapettit]

It doesn't matter how I configure the inputs or where they are pluged or which of the two bulbs I use the left side is still yellow! VERY FRUSTARTED!

[dapettit]

After all the troubleshooting it looks like its the mogul base. It's either crosswired or just plain bad. How do I know your ask? I removed the bases from both reflectors and put the know good on the side I was having problems. Screwed in the bulb, connected the cable to the suspect input on the ballast, powered the ballast on and presto changeo we have white light. Since my eyes are really bad I'll check the suspect base in the morning.

Thanks for all the input. I'll keep everyone posted. . .

[kcress]

Most interesting!
Thanks for keeping us posted.

I've been thinking about it.. Here's my theory now. The current thru the bulb is a function of the bulb's design and the ballast. That should be it. They are made for each other.

Along comes a socket with a problem. It can be frayed wires,(Yikes!), or the socket's center contact doesn't press firmly on the bulb's center pin, or your mod'd wiring is somehow not getting the full connection correctly. The result will be resistance. This resistance is unexpected in the system design. The result will be reduced voltage and current thru the bulb. MH bulbs are carefully designed to operate at a specific power. You cannot dim them as they just will not work correctly.

They work, as I think I mentioned, by keeping a mixture of metals so hot that they are in vapor form - a gas. The light generated is caused by the precise mixture of gases. With the reduced power to the bulb from a high resistance the metal mix will be wrong and the color will then be wrong.

By-Jove I think you've found the problem.

[dapettit]

Thanks for explaining, I couldn't have done it better. The center contact wasn't firmly on the bulbs center pin. I must have bent it while re-wiring. You would think with an engineering background I would have figured ti out. It's always the simple things.

[kcress]

So did you just "bend out" the contact and it works now?

[dapettit]

The mfg. will replace it just in case there are other problems. I will keep you posted. . .

[dapettit]

The mfg replaced the mogul base. I re-wired everything and viola, it works!

[kcress]

Outstanding!
Let there be light!!(non-yellowish)