GLA Lamps - Infant Mortality - did I do anything wrong?

[DavidM]

Several years ago we picked up 6 Strand Lekolite fixtures (6 x 12, 2112) from a local theatre that had them sitting in the basement for our church platform. They are a whole lot nicer than the par38s (GE 100W Spot) we had previously. They were lamped with 1000W FEL lamps. Recently we ran out of replacement lamps and I looked into ordering more. Found ControlBooth and read several threads about FEL and "ship's" strong suggestions to replace them with GLA lamps. (575W 115v)

I found a supplier in Canada (Vancouver) and ordered 4 new GLA. They source them out of China and claim to have had great results.

At the same time our (3-5 yrs new) local high school (where my son and his friend-grade 10) run sound and lights was having bulbs burn out. The administration has no idea about ordering replacements. The fixtures are source 4 knockoffs using Thorn HX601 lamps. When the first lamp burned out about a year ago I suggested strongly that they get in a stock of bulbs because with all the fixtures in service at the same time the rest of the lamps were likely near end of life too. This year the high school has 8 out of a total of 14 fixtures dark and still hasn't ordered lamps(!) From the threads here I figured a GLA is the suggested replacement for the HX601 as well, so I put two of those new lamps into the fixtures at the school for the "Cinderella" play they did this spring. Worked great right out of the box.

Come last Saturday I finally got around to relamping our fixtures at the church (the Strand Lekolites).

Both bulbs blew as soon as power was applied. Fed by dimmers that have run FEL (1000W bulbs) in these fixtures for the last couple of years. Power voltage measures 117-118 @ the dimmer pack output when I went up later the next day to check.

In detail: I installed the first one, went down to the dimmer, slid it
up and poof, the bulb was gone.

Installed the second in another fixture across the room. Plugged it
in and tried it at low power just to be sure it was working (this is
in the socket, not put back in the fixture yet). It glowed dimly at
low power, so I inserted the socket into the fixture (being very
careful not to hit the bulb on anything), slid the
dimmer up and poof it went out as well as it came to full brightness.

2 lamps in 10 minutes is a bit disconcerting...

I know not to touch the lamps - I used the foam packaging the lamp was
packed in to handle and install the bulb, no skin contact. I was
careful not to hit the fixture with the bulb when putting it back in.

The blown lamps are not blackened - don't even look used. It appears
the filament burned off at the side where it connects to the main wire
down through the base. (I've tried to attach a picture. The filament
break is on the upper left corner of both lamps.)

Is there anything obvious that I have done amiss? I was recommending
a purchase of 12 more GLA bulbs at the high school, but I am not
totally confident of making that purchase right now.



The supplier is standing behind them, but concerned about the "higher voltage" of 118 Volts. I'm enough of an electrician to know that 3 volts is insignificant (esp. by the time you add 80-100' of 14/2 between the dimmers and the fixtures) BTW - how much higher would the voltage have to be to blow the lamp right away? 25%?40%?

Thank you
David Meed
Hartland, NB Canada - home of the longest covered bridge in the world

[JD]

Voltage was not the issue, or the cable. No sign of oxide such as air entry. The filament broke in the exact same location on both lamps. I suspect factory defect that had to do with how the filament winding was twisted as it met the lead-in wire. Make sure if you get replacements they are from a different batch. Doesn't look like anything you did.

Over-voltage can blow lamps, but usually just decreases lifespan. Running a 115v lamp at 130v would more than half the lifespan, but an instant flash-out would probably not happen unless you were over 150v. (In fact, there used to be a company that marketed a booster transformer to get extra brightness.)

Once a lamp arcs, additional damage can be done. I see on one lamp, both ends are blown. Still, when the filament breaks at a twist point, I get suspicious about defects.

[techieman33]

Just one of the many reasons to stay away from cheap Chinese lamps.

[derekleffew]

...I found a supplier in Canada (Vancouver) and ordered 4 new GLA. They source them out of China and claim to have had great results. ...
The supplier is standing behind them, ...

Good that the supplier is replacing them at no cost to you (other than associated hassles), but is the headache worth it? To save one or two dollars per lamp? I'd always choose Osram/Sylvania, GE, Phillips, Ushio (in that order, largely due to DELO72's involvement with ControlBooth), with generic imports as a dead last resort.

Those who buy a lot of lamps develop actual or perceived opinions as to which brand is best. There may be no factual basis, only personal feelings, but once one finds a Brand he likes, he tends to try to stick with it. Most agree that generic "no-name" brands, especially from Asia, are just not worth the risk.

I don't know how importing to Canada works, but a quick Internet search finds GLA by Phillips for $16.35, GE for $17.70, and Osram for $17.89. All US dollars, all US companies.

It's nothing you did, it's not the voltage, you simply got a bad batch.

[josh88]

I have to agree, I'm using Ushio because that's what I can get from my supplier, but I'd take osrams as my first choice every day of the week.

[DELO72]

I have to agree, I'm using Ushio because that's what I can get from my supplier, but I'd take osrams as my first choice every day of the week.

Then you aren't pushing them hard enough! :-) Or you need to find a new supplier!

Over-voltage can blow lamps, but usually just decreases lifespan. Running a 115v lamp at 130v would more than half the lifespan, but an instant flash-out would probably not happen unless you were over 150v.

Actually, this is not correct. The Rule of thumb is never to operate a lamp over 110% of it's rated voltage. For a 115V lamp, this means if you go over 126.5V, you can expect 30% of it's rated life or less. At 130V, it could fail at any time, and higher than that... well, go buy new lamps.

They could have failed for any number of reasons (a weakened or damaged filament, wrong fill gas mixture or pressure, etc.). Always buy Name Brand is my advice. It's not that we also don't have production issues from time to time (hey, we are all human), but our consistency and quality control tends to be better overall than at the smaller players.

Regards,

Mark

[tyler.martin]

Any vendor such as Christie Lites, and Epic Production Tech. do stock the GLA, at least they do in Vancouver, so should the office in Toronto, Winnipeg or even Halifax.

[cbrandt]

Then you aren't pushing them hard enough! :-) Or you need to find a new supplier!



Actually, this is not correct. The Rule of thumb is never to operate a lamp over 110% of it's rated voltage. For a 115V lamp, this means if you go over 126.5V, you can expect 30% of it's rated life or less. At 130V, it could fail at any time, and higher than that... well, go buy new lamps.

They could have failed for any number of reasons (a weakened or damaged filament, wrong fill gas mixture or pressure, etc.). Always buy Name Brand is my advice. It's not that we also don't have production issues from time to time (hey, we are all human), but our consistency and quality control tends to be better overall than at the smaller players.

Regards,

Mark

You should tell that to the guys that designed the Q1000 follow spot (and QF1000). It has a transformer that over drives an FEL1000 at 150 volts. Destroys lamps in no time, and you have to break them to get them out of the fixture.

[JD]

You should tell that to the guys that designed the Q1000 follow spot (and QF1000). It has a transformer that over drives an FEL1000 at 150 volts. Destroys lamps in no time, and you have to break them to get them out of the fixture.

Yea, remember a whole bunch of "boosters" out there. Had one that ran FEL's at 140 volts on the Altman 1000Q. Nice and bright, but watch how hard you slam the color boom! Not a big fan of them, and once good HMI spots came out, they all but disappeared. Also remember a club band that ran the lamp off of a 140 volt variac. They kept it dialed down to ~120 except for certain cues. Claimed it wasn't costing them much life. Key word, "Claimed" !

Most of those transformers were soft enough that the inrush wasn't harsh, as the output voltage would collapse a bit when you hit the switch on cold inrush. I suspect a hard 140 or 150 volts with no collapse at turn on would kill them off pretty fast.

[Chris Chapman]

I had the same issue with a box of brand spanking new USHIO HX600's. It was a bad lot. I went through BMI as the vendor and they happily replaced at no cost. Some times you run into bad lots.

[derekleffew]

Yea, remember a whole bunch of "boosters" out there. Had one that ran FEL's at 140 volts on the Altman 1000Q. Nice and bright, but watch how hard you slam the color boom! Not a big fan of them, and once good HMI spots came out, they all but disappeared. Also remember a club band that ran the lamp off of a 140 volt variac. They kept it dialed down to ~120 except for certain cues. Claimed it wasn't costing them much life. Key word, "Claimed" !

Of course, today we know differently:

lumens/LUMENS = (VOLTS/volts)^3.4
life/LIFE = (VOLTS/volts)^13

An FEL run constantly at 140V will be 169% brighter, but will live only 13% of its miserable life.

However, sometimes it's necessary to eek out every last lumen:
[Posted by STEVETERRY to the wiki entry dimmer, autotransformer :]

A common variant of autotransformer, the Variac, also allows boosting the input line voltage to about 140V by placing the input tap on the transformer between the maximum end-of-travel of the carbon brush and the 0V neutral tap. This type of device was used on the 1975 Broadway production of A Chorus Line to boost the voltage to the 1000W FEL lamps in the Strong Trouperette III followspots, to gain additional brightness.

See also the thread Colortran Trivia for the device referred to in post #2. Colortran = Color Tran(sformer).

coltemp/COLTEMP = (volts/VOLTS)^0.42