I spent most of yesterday afternoon giving the lightshow at Dragonfly its semi-annual heavy-duty cleaning. You wouldn’t believe the kind of crap that gets inside these things, and without regular cleaning they tend to either malfunction badly or stop working entirely. Read on for the details.

The last time I cleaned the lights was back in September ‘05. In the ten months since, the lights have gotten so caked with dust and dirt that they are no longer as bright as they should be, and the colors have shifted badly. Worse, two of the four MAC-250s had completely failed, and the remaining two were on their last legs, giving all manner of tracking errors. Additionally, one of the MX-4s had blown a bulb, and all were nowhere near as bright as they should have been.

The process begins by taking the four MAC-250s off of their mounting brackets. Although they only weigh about 70 pounds, you have to hold them at arm’s length 16 feet off the floor during the process. Not fun. Each unit gets set down on the “workspace” (short bar) and gone over with a fine-tooth comb (actually, concentrated glass cleaner, rubbing alcohol, distilled water, microfiber cloth, and a 135 psi air compressor). Each 250 has four glass lenses that get caked with dust and dirt, and each lens has to be removed and cleaned. Then, the base of the unit (which stores the lateral-axis motor, power supply, and logic boards) gets the dust blown out of it. Once the base gets cleaned and re-sealed, the head gets completely disassembled, dusted, and reassembled. The color wheel (a rotating wheel containing 18 tiny pieces of tinted glass) gets scrubbed, and the gobo wheel gets dusted out. Finally, each lens gets re-seated. This is an especially important process, since the lenses are all spaced and oriented in a very specific manner to yield proper beam focus and dispersion angle. Once that’s complete, the head gets re-sealed, and the unit goes into bench test mode for about 30 minutes. Total time per unit, excluding bench test, is about 90 minutes. Four heads + testing time = 8 hours cleaning four lights.

The next step is the MX-4s. These are a lot easier to clean, largely because they’re much simpler. Each unit has two lenses, a mirror, and a color wheel (the gobo wheel is a piece of stamped metal that really doesn’t need much maintenance). All I do here is take off the plastic shell, blow compressed air back through the exhaust port, and watch several pounds of dust and debris fall to the floor. Then it’s a quick one-sided wipe of the color wheel with glass cleaner, an alcohol bath for the lenses, and a wipedown of the mirror with concentrated cleaner & a microfiber cloth. The only hangup with the MX-4s is that there can be absolutely no streaking or marking on the mirrors. Since these have a 150w discharge lamp on at all times, any imperfection in the mirror will show during operation. Not pleasant (at least not for me).

You can check out the results in my Flickr stream.  I’ve also thrown in some night pictures (I work all day, thanks) of the “flood”.  In a few days, I’ll post a few pics on the success or failure of the process.