My Overhead Projector Has What?

Over the previous 25 years I’ve had the distinctive alternative to speak immediately with lots of the professionals and instructors who use Overhead Projectors as an integral a part of their occupation. Via these interactions I’ve accrued notes and data that has impressed me to put in writing these articles that pertain to a few of the most typical issues skilled by homeowners of immediately’s and yesterday’s Overhead Projectors. That is the fifth article in a sequence of

articles that will likely be written from an expert Electronics Technicians viewpoint with reference to a few of immediately’s most typical Overhead Projector issues.

My shoppers usually 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, typically known as rectifiers. Diodes are semiconductor gadgets which may be described as passing present in a single route solely. You’ll be able to even discover diodes utilized in a few of immediately’s LED (gentle emitting diode) Flashlights. Within the case of Overhead Projectors, diodes are used to manage voltage.

With the appearance of immediately’s halogen projection lamps utilized in most Overhead Projectors immediately, a particular working voltage is required to function these lamps. Typically 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 top person, when the diode of their Overhead Projector fails it may be fairly pricey. Most finish customers do not realize that this part 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 discuss with this as scorching. The top person assumes that they’ve a faulty projection lamp, so one other lamp is positioned into the projector. This course of typically continues on with a number of lamps being changed earlier than the top person realizes that it isn’t a faulty projector lamp inflicting the issue.

The diode is a reasonably cheap digital part to exchange and typically is well accessible. The one warning I have to supply right here is that diodes are directional and should be positioned again into {the electrical} circuit a specific means. In case you are not accustomed to all these parts the restore ought to be left to an expert digital technician.

Supply by Mark Boehm

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