Wednesday, March 21, 2012

I only have one rule: DON'T do this to your data projector!

My supervisor brought her Proxima data projector to me today. The picture is very dim, she said, and could I take a look at it? So I took her projector to the test bench to see if I could discover the problem.


The first thing I did was open the little access panel on the projector and remove the bulb. What the heck was wrong with it? As you can see in the photo, the heat-absorbing glass in front of the bulb was melted and fractured. So then I looked at the lens cap and saw that it had begun to melt. So riddle me this....what would cause the glass panel on the front of the bulb as well as the lens cap to melt?

Right. Someone had powered up the projector and then placed the lens cap over the lens. All of that high intensity light was shooting out of the bulb, hitting the lens cap and reflecting back into the bulb housing. That creates a tremendous amount of heat; enough to melt a quarter inch thick piece of glass that is specially designed to absorb heat.


Normally, this would mean buying a $120 lamp to replace the one with the melted glass. However, I was fortunate enough to have a burned out lamp of exactly the same make and model. Removing the melted glass from one and replacing it with the intact glass from another allowed me to make the repair for nothing. Just dumb luck that I had not thrown away the bad bulb a week earlier.

As Barney Stinson says on TV, "I only have one rule." And my rule is this: NEVER, NEVER put the lens cap on a data projector while the bulb is lit. You will ruin your expensive bulb and also perhaps your expensive projector.