stage lights & bulbs

I am a band director in our public school system. As of this year, I am in a newly created Auditorium Manager position. This position was created mainly because of scheduling nightmares that had been occuring. I have been running the lights and sound for our school's concerts for the past 17 years, but I know just the very basics and enought to make things work for the concerts - nothing fancy. I can set up our sound equipment and patch in lights to the board. Though, if things go wrong with the equipment, I have to contact our technology coordinator and hope he can/will fix them.

Our lighting equipment (including the board) is old, but they work. How do I know what kind/style of stage lights we have? How do I know which bulbs are supposed to be used in those lights? A custodian has changed the bulbs in the past, but when I went to change some bulbs last month, the old bulbs had bubbled in the fixtures to the point where they had created a hole in the bulb and then the glass section of the bulb just pulled out of the base, leaving the base in the socket. One of the bulbs had actually exploded in the light fixture. The custodian came to help me at this point, and the new bulbs he put in the fixtures seemed awfully big for those fixtures. He said they were the bulbs he always used for those lights. How do I know if we are really using the right bulbs? I need to order some new bulbs, but I don't want to order the wrong ones just because "they're what we've always used". All I really have to go off of is his word - no one else on staff knows anything about the lights, and we have no manuals around.

ANY suggestions you would have for me would be greatly appreciated.

 

We definitely have a few that look like the first picture. We used bulbs that look like car headlights for those. I think the others look like the second picture, only MUCH older.

 

Gaff's post is eloquent in it's simplicity. Are there any markings, names, anything on the instruments themselves? Or pictures might work too.

 

The "headlight instruments" should look like this:



Does it look like this? If so it's called a PAR can, they come in varying sizes.

Here is another picture of the second instrument:



This is a fresnel, it has the ridged lens.

 

Good idea. I'll get pictures of the lights tomorrow and post them.

 

Whoa! Hold up, where is this handle you speak of on the par cans? Wow, after coming to these boards I realized two things. 1. I know nothing at all. 2. My school could teach us more.

 

I'll take a look at our pars when I get a chance. I haven't noticed any handles... yet. Thanks.

 

Many brands of Par cans don't have a handle. You simply reach in through a hole in the rear of the fixture and rotate the porcelean connector to orient the beam.

 

The newer PAR cans do not have an access hole in the back, the code requirements require this to be closed off to stop peopole reaching in and getting an electric shock

 

That is true. However it is still a simple thing to open the rear assembly of a par can and rotate the bulb.

 

It’s called finger [email protected]&ing. Where the oil from one’s skin touches the lamp and it caused the halogen effect to improperly cool by way of heat reflected off the oil coated surface. Bad thing to see, once did in an entire theater’s inventory this way myself early on no doubt in a similar era of understanding what the heck I was doing beyond functioning. Still have some of them bubbled lamps, at times the filament would stretch as if blown towards the bubble to the point that the filament itself would encase itself within the glass. It would still work even if surrounded by the glass outer bulb. This until at least it finally had a blow out.

This all as opposed to real blow outs where the filament possibly due to a voltage spike while already operating at times will shoot thru the outside wall of the glass in the glass having like a bullet effect worth of hole frozen in it, and the opposing side of the lamp having a puckered like appearance due to the gasses sucked out of the lamp.

This also as opposed to the bloated lamp where someone did a really good job of touching the lamp and there is a huge bubble blown up all over the globe as if balloon. Such lamps often have a silver coloring to them due to the deposits from the filament finding the outer globe of the lamp hotter than the filament at some point before it also fails.

Love lamp failure science, at times at work, it’s as if I am the CSI of lamps - who did what. This especially for metal hallide type lamps. This past weekend I had a HSR 575/72 lamp that had something like 4,950 hours on a lamp rated for 750. Sent the “looks brown” lamp back for another play test, why stop now, let’s at least take it up to 5,000 hours before replacing it. Next lamp by chance had over 9,500 hours on it... Took a look at the amount of bubbling and wear to the electrodes, yep, this lamp has been in service for about 40 hours in reality, but we have a new world’s record in a lamp I now have no chance of returning to the manufacturer due to also being “brown” in look to it but our not re-setting the lamp life counter on lamps changed in this fixture. Hmm, over 9,000 hours... that means at least the last 12 lamps installed in this fixture have not had the lamp counter on the moving light reset. I tack the fixture serial number and know who the idiots “professional lighting technicians” are that don’t know how to re-set a lamp counter...

Anyway, lamps doing odd looking things like getting bubbles are often from people touching the lamp. Sections of the filament that fall off a hanger or in having a broken hanger kind of fall off and go off free hanging or at an angle in also at times touching the globe often comes from rough handling of the fixture.

Be sure and examine the lamps and fixture sockets each time a lamp is changed - look for arching and corrosion as a tell tale sign of something that needs either re-surfacing - an advanced technique or replacement. Short of having a look at what went bad, you will burn thru what’s good in making it arch it’s way into being bad.

Get the gear including and especially beyond the lights also in need, specifically the dimmers and board in for a yearly service call like yesterday if you want to depend upon such things working tomorrow. Budget for doing this professionally yearly or you need to start budgeting for new equipment instead at a higher cost immediately.

Start studying for your new trade. Lots of good books out there and good past posts here and say on Stagecraft to read. You are responsible now for the gear it would seem, time for you to be responsible for it and not rely on anyone other than leg work for assisting you. This much less maintaining it to your new acquired studies in standards for the gear. Could be this technology coordinator is doing a perfectly fine job, could be and often is otherwise. You need to know the difference. Perhaps take a course at the local college or junior college in stage lighting to supplement other studies of it. Gotta master beyond being able to function as it’s your responsibility this lineage and supervision.

Each fixture if produced after like 1960 will have as if your coffee pot a stamp on it that lists it’s rated wattage, voltage, manufacturer and model. That’s a good start. Take a list, heck, pull down all the gear do a cleaning and service call, figure out what needs attention and do a good inventory. When is for instance the last time the bolts on the C-Clamps have been oiled?

IN knowing what’s the right bulbs (Lamps - bulbs grow in the ground or describe the shape of the glass on a lamp), you have to know what fixtures you have. AT times, a lamp will be larger, at other times say a hole in a reflector is not sized for the lamp installed and say if closer than 1/16" to the reflector, it’s not the correct lamp or you need to modify the reflector. Another factor is bench focus - that state when the lamp is correctly centered optically within the reflector and lens system. A lamp too close to a reflector could also not cool properly and cause a bubble or blow out if not explosion if torqued against the reflector. Gotta do a bench focus where possible each time with older fixtures, this if not at least a rough sighting of where the lamp is sitting in the fixture by way of inspection after installed.

Lots of causes for what you have observed so far, you are the person on site. It’s going to take some leg work and lots of study to gain control of what you now are responsible for. Enjoy and live this time where you will learn ever so much. Ask lots of questions also.