Over the previous 25 years I’ve had the distinctive alternative to speak immediately with most of the professionals and instructors who use Overhead Projectors as an integral a part of their career. By these interactions I’ve collected notes and data that has impressed me to jot down these articles that pertain to a number of the commonest issues skilled by house owners of as we speak’s and yesterday’s Overhead Projectors. That is the fifth article in a sequence of

articles that shall be written from an expert Electronics Technicians perspective with regard to a few of as we speak’s commonest Overhead Projector issues.

My purchasers typically say to me “You suppose my Overhead Projector has a nasty diode, what’s a diode?”

Let’s begin off with fast lesson about diodes, generally known as rectifiers. Diodes are semiconductor gadgets which is likely to be described as passing present in a single route solely. You’ll be able to even discover diodes utilized in a few of as we speak’s LED (gentle emitting diode) Flashlights. Within the case of Overhead Projectors, diodes are used to manage voltage.

With the arrival of as we speak’s halogen projection lamps utilized in most Overhead Projectors as we speak, a particular working voltage is required to function these lamps. Usually the voltage is round 82 volts. As a result of the voltage on the AC outlet the place you plug your Overhead Projector into is 120V AC, a diode (rectifier) is used to manage this line voltage to the required 82 volts.

Sadly for the tip consumer, when the diode of their Overhead Projector fails it may be fairly expensive. Most finish customers do not realize that this element even exists. When it fails, in most situations the diode turns into a brief circuit. This brief circuit permits the road voltage of 120 volts to go on to the projection lamp which solely requires 82 volts to function. In our restore store we check with this as scorching. The tip consumer assumes that they’ve a faulty projection lamp, so one other lamp is positioned into the projector. This course of generally continues on with a number of lamps being changed earlier than the tip consumer realizes that it isn’t a faulty projector lamp inflicting the issue.

The diode is a reasonably cheap digital element to exchange and normally is well accessible. The one warning I need to supply right here is that diodes are directional and have to be positioned again into {the electrical} circuit a selected means. If you’re not acquainted with some of these elements the restore ought to be left to an expert digital technician.


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