For the past few days I have been trying to track down a phantom problem.  It is only phantom in the fact that I can’t reproduce the problem outside of the show.  That, I suppose, makes it definable is an intermittent problem.  This of course, is the most difficult of problems to diagnose and to solve.  Certainly a very frustrating problem.

What is the problem?  Well, I have a moving light that seems to intermittently decide to just quit.  For those of you who are not theatre people,  or don’t work with many moving lights, this particular fixture uses an arc discharge lamp.  That means that the light is created by maintaining an electric arc between two electrodes.  It is very similar to the arc that is used in arc welding except that it is contained inside a lamp.  Here is a photo of the lamp, just so you can see what I am talking about:

This is the HTI 700/D4/75 arc discharge lamp. This particular lamp has 99 hours of burn time on it. You can see the "arc gap" in the center of the globe, this is where the electric arc is created. The arc excites gases in the globe and emits light.

So, a few day ago this problem showed up.  We made it through tech and most of the first week of performances before the problem began.  The fixture drops the arc (douses out) and displays a lamp error message.  So my initial thought was that it was a bad lamp.  While this is rare, it is possible, and the least expensive problem to fix.  In fact, with a lamp this “young” (only 99 hours into it’s 1000hr rated life), if the lamp failed I could make a warranty claim for a new lamp.

Unfortunately the lamp seems to not be the problem.  I installed a brand new lamp and the problem persisted.  Thanks to my friends over at controlbooth.com I had lot of other suggestions of things to try.  Some are not really feasible at this point in time, but after the show closes I can try them.  Today I actually got up in a focus chair to string a new circuit for this fixture that takes it off of the dimming system to eliminate any power issues that may have occurred there.

Well, I have been unable to solve the issue, which leads me to believe that the problem lies in the fixture and not the lamp or the power feed.  This probably means a more expensive fix, but I am sure that I can have it fixed.  Though I would certainly take any advice any theatre folk may have!  Such is the nature of life in the theatre.  I just like to look back on my favorite quote about the theatre from the movie Shakespeare in Love:

“…allow me to explain about the theatre business.  The natural condition is one of insurmountable obstacles on the road to imminent disaster!
…Strangely enough, it all turns out well.”

I made my PTC stage debut today in quite an unfortunate situation.  We had a flying piece that snagged on one of our curtains as the curtain was moving and it broke one of the pick lines.  These pick lines are made of 1/8″ steel aircraft cable, so it take a pretty goodly amount of force to break them.  It seems that as our nice velvet drape was going out (up) it snagged the scenery, a lighted sign, and probably lifted it and then dropped it, breaking one of the two cables.  I think that my electric cables were probably bearing some of the load of the sign.

Well, we saw this thing swing into view and immediately stopped the show.  We cleared the cast off the stage and removed the piece of scenery.  In all it probably took less than ten minutes to do all the work, but it felt like forever.  The adrenaline was still pumping as I started to write this.

It is amazing how things slow down when you are in action mode.  I also think that it is interesting that some people feel like the shows problems can be solved with the biggest hand-held cutting tool that you can find in the shop.  All we had to do was disconnect the rigging hardware and unwire the electrics and the piece was free.  It was probably a good thing that I was mostly calling the shots with the removal of the piece or things might have ended up getting cut.

I remember getting out on stage and helping one of the ASMs get the piece on the deck.  Then there was some cheering from the audience.  Then I disconnected the electrical and rigging hardware and the crew took the piece off stage.  I capped the electrical and then they were about to take the lineset out when it finally occurred to me that the aircraft cable had broken and was just hanging on by tape.  So, we removed that as well and got the line out and clear.  The strangest thing was that I left the turnbuckle in the shop but for some reason I ended up taking the broken cable back up to the booth with me.  Stranger things have happened.

That was the excitement of the evening.  It wasn’t good excitement, but it excitement none the less.  One more show for the books I suppose.