Over the past 25 years, I have had the unique opportunity to speak directly to many of the professionals and instructors who use overhead projectors as an integral part of their profession. The stories you’ve shared with me have given me direct insight into some of the most common problems experienced by overhead projector owners today and yesterday.

I would like to share this unique collection of information with a series of articles derived directly from some of the most common questions and complaints that I receive from my clients in the Audiovisual Industry.

The first thing that comes to mind is the question I am asked almost every day; “My overhead projector keeps burning lamps, what could be the problem?”

Most of today’s overhead projectors use projection lamps that require 82 volts to operate. Because the AC outlet you connect your overhead projector is 120 volts, a special electronic component is required to create the 82 volts needed to operate the projection lamp. This electronic component is called a diode (rectifier).

When the diode (rectifier) ​​in your overhead projector fails, it allows the 120-volt line voltage to go directly to the 82-volt lamp. This extra voltage is too much for the projection lamp to handle, when the user turns on the overhead projector, the projection lamp will burn out within seconds due to this excessive voltage. In some cases, the end user will fit several new lamps into the overhead projector before realizing that the problem is not a faulty projection lamp.

If you have a basic understanding of electronics or basic wiring, the diode is something that most end users can replace themselves; otherwise, this problem should be handled by a professional service technician.