Saturday, May 17, 2008

Projection Lamps And Premature Burnout

Writen by Mark Boehm

Over the past 25 years I have had the unique opportunity to talk directly with many of the professionals and instructors who use Overhead Projectors as an integral part of their profession. Through these interactions I have accumulated notes and information that has inspired me to write these articles that pertain to some of the most common problems experienced by owners of today's and yesterday's Overhead Projectors. This is the ninth article in a series of articles that will be written from a professional Electronics Technicians point of view in regards to some of today's most common Overhead Projector problems and questions.

This is part two of my article titled "Projection Lamps; how long should they last?" Because of the response I have had from the first article I thought it might be a good idea to continue our discussion of the subject of projection lamps and premature burnout.

One of the most frequent questions we receive from our customers is what causes early projection lamp failure. A lot of people are making simple mistakes that end up costing them a lot in burned-out lamps.

For instance, did you know:

• Moving the Overhead Projector while the lamp is on or even shortly after turning it off can cause premature failure. A hot lamp filament can easily be damaged if handled roughly while still hot.

• If an Overhead Projector lamp does not burn out immediately, but burns out within an hour, the lamp is probably defective, not the projector. In many cases diode failures are the cause of many burned out lamps. However, a diode failure will usually cause a lamp to burn out instantly!

• You should never move a lamp changer lever (if your machine is so equipped) while the on/off switch is in the "On" position. This will jar the lamp and cause a hot lamp filament to fall apart. Moving it when the power is off will assure the lamp filament is cool and able to handle rougher treatment.

• Excessive heat will shorten lamp life. A fan motor running slow due to lack of lubrication or excessive dirt will not cool a lamp sufficiently or damage to the fan blades will reduce the cooling efficiency of the fan. A regular maintenance program will help prevent this from occurring.

• You should never allow anything to block the airflow of your projector's cooling fan. The intake and output grills must not be obstructed or overheating will occur, shortening the life of the projection lamp.

Mark Boehm is the president of M-B Electronics He has over 25 years of experience in the Audio Visual and Electronics Industry. You can contact him by calling 800-872-9456 or by e-mail at:

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