# Halogen bulb keeps burning out



## jagwirez (Oct 11, 2009)

Hello all, thanks in advance for any advice given.

I am the LD at a church. We have a pretty dynamic style of worship using 4 movers, haze and different types stationary fixtures.

We have 2 Seachanger Wash lights, using ETC Source 4s. One of those have blown at least 5 bulbs (HPL 750w halogen lamp). I have done many things to prevent it. I have changed the circuit, dimmer, changed the source four fixture, moved the hazer around. 

To get a better picture, they are hanging on our 1st electric (1/3) at the ends pointing down to the opposite end of the stage, so they cross paths when lighting. The hazer (water based, Le Maitre Radiance) was on our backstage mezzanine 15 ft away blowing that direction. I moved the hazer downstage so it wasn't blowing directly on the lamp. Moving the hazer and changing dimmers (C21 Strand Lighting) was the last attempt I did to fix it.

It's been 2 weeks so far with no blow out, but the other Seachanger lamp went out across stage. That was the first time this one went out.

I am just wondering if anyone had any experience like this or know any other possibilities. These halogen bulbs seem to be very vulnerable so I guess anything is possible. Thanks for your help.


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## photoatdv (Oct 11, 2009)

Possible causes... in no particular order:

-contaminants on the lamps (is someone toughing them when they are replacing them?)
-Bad lamp base (is the filament broken? or is it just not working?)
-Cooling problems
-Bad batch of lamps
-Power problems (sounds like you've mostly eliminated this...)

I'd look at the dead lamps very closely (and maybe post a pic for ship). Try cleaning the new ones with isopropyl alcohol to make sure they really are clean. Make sure nothing's obstructing airflow around the units. Make sure they aren't super dusty. I'm sure ship will be around soon with more lamp advice


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## starksk (Oct 11, 2009)

In addition to what photoatdv said, I would also look at the voltage of the HPL in use.

Assuming you are in the US, there are two voltages for the 750W HPL that are commonly used: 115 and 120. If you are using 115V lamps and you are feeding it with more than 115V on a consistant basis, you will see poor lamp life. 

So, in your troubleshooting, I would also meter the circuit(s) that you are using to see your actual voltage output. (Be sure to use a RMS voltmeter as the chopping of the sinewaves that occurs with dimmers can lead to false voltage readings.)


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## icewolf08 (Oct 12, 2009)

Also consider that the rated lamp life on the high output version of the HPL lamps is 300 hours or 12.5 days. So, depending on how long you burn your fixtures over a two to three week period, you may require frequent lamp changes.

However, the problems listed above are probably more relevant. When you look at the dead lamps, make sure you look not only at the filament and glass, but also at the pins. If there is any evidence of corrosion, charring, burning, or strange looking metal deposits then you have a bad lamp base. Putting a new lamp in a bad base will cause the same thing to happen. Replacing the base is easy and should only cost about $20.


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## waynehoskins (Oct 12, 2009)

I was thinking dead ceramic too. I've got two of those in my set of 360Qs that I need to replace -- if I use them, they just keep killing lamps.

Long-life (130V) lamps would be a very good option. I also agree it's very possible to have a bad batch of lamps.


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## jagwirez (Oct 12, 2009)

Thanks for your inputs, I looked some more and see that the bulbs are rated for 115v, and the dimmer system puts out about 119, so I may lower the voltage for those. All of the source 4s in the catwalk do great and have only lost a couple lamps in the last almost 4 years. I just didnt know if these two were acting up because of the hazer, bad batch, too much heat from the seachanger. Just wasn't sure.


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## icewolf08 (Oct 12, 2009)

Chances are, the voltage thing is less of a problem than you think. Many people buy the 115V lamps for use in 120V systems for that little bit of extra punch. It shouldn't really effect the lamp life too drastically, and if your other fixtures are fine then it would seem to indicate a different problem.


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## Clifford (Oct 12, 2009)

Our entire district buys 115V 575W HPLs for use with our 120V dimmers. I've never had a problem with lamp life (except when new students are given new lamps).


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## jagwirez (Oct 12, 2009)

Ok, sorry I don't have pictures, but maybe this can help. Most of the lamps that blew, had white risidue on the glass. I made sure to not touch them when installing. This led me to think it could be the hazer. I moved the hazer so the light is not in it's direct path, and so far that one's been ok.


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## JD (Oct 12, 2009)

Just one other thing to consider; Vibration or motion. Since filaments operate so close to the melting point, it doesn't take to much to blow them. Often when failures are location specific, vibration can be a hidden culprit.


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## jagwirez (Oct 23, 2009)

Just an update. I used a completely different SourceFour in another room on a separate dimmer pack, put a brand new HPL lamp in it. It worked fine, and then the next day, it wasn't working. I check the bulb and it was black and blue all over, similar to some others that blew. This bulb was from the same batch of all the others that blew. They are all Osram, but I can't blame the manufacturer, I know they are a good brand.


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## derekleffew (Oct 23, 2009)

Even the best of manufacturers put out a bad batch occasionally. Any reputable dealer should replace the entire batch for you, and then deal with the manufacturer to get its refund. Keep as many of the burnouts as you can, and take the entire batch back. Sounds like it could be a pinch seal failure.

Another reason to support your local dealer (see Best Dealers for Supplies & Equipment), although most online dealers would do this as well.


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## FMEng (Oct 25, 2009)

jagwirez said:


> Just an update. I used a completely different SourceFour in another room on a separate dimmer pack, put a brand new HPL lamp in it. It worked fine, and then the next day, it wasn't working. I check the bulb and it was black and blue all over, similar to some others that blew. This bulb was from the same batch of all the others that blew. They are all Osram, but I can't blame the manufacturer, I know they are a good brand.



I'm not so sure about Osram being good anymore. I got a batch of Osram FEL lamps whose base pins are clearly not to specifications. They practically fall out of the socket and do not make good electrical contact. The GE's and Ushio's work fine in the same sockets. My advice is to try a different brand before jumping to any other conclusions.

Did you measure the applied voltage where the instrument plugs in and with the light running? You have to measure the voltage there under load, not at the dimmer. The 115V lamp is rated at that voltage because there is usually a significant voltage drop in the wiring between the dimmer and the instrument. A true RMS voltmeter is essential, too.


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