Hughes JVC 220, Service Manual

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Chapter 2---System Description
Combining (4P) Prism: The combining prism consists of
separate prisms that polarize each of the three high intensity
signals and direct them toward the projection lens.
Projection Lens: The Projection Lens picks up the high intensity
image from the Combining Prism and transmits it to the projector
screen.
2.2.2 Arc Lamp Light Path
The Arc Lamp assembly produces the high intensity light used to
transmit bright images to the screen. It consists of a Xenon Arc
Lamp containing xenon gas under pressure, a Condensing Lens
bolted to the arc lamp housing, an Ignitor assembly that provides
the spark to light the arc lamp, a Laser Power Supply to provide
the boost voltage to the Ignitor. An exhaust fan helps keep the arc
lamp cool. The description below follows the sequence of the light
path. (
See Figure 2-1) .
Ignitor and Laser Power Supply: The Laser Power Supply
provides a boost voltage through a spark gap to the Ignitor circuit
which then provides a momentary High Voltage, (about 32 KV), to
excite the xenon gases inside the Xenon Arc Lamp. After the arc
lamp ignites, it is maintained ON by high current and low-voltage
(approximately 47.5 amps and +20 volts). The Ignitor and Laser
Power Supply are mounted on the base next to the arc lamp.
WARNING!!!
The Xenon Arc Lamp produces high
intensity white, ultraviolet and infrared light capable of severe eye
injury.
Never look directly at or touch the Xenon Arc Lamp.
Service should be performed by Hughes-JVC certified
technicians only.
Xenon Arc Lamp/Condensing Lens: High pressure, ionized
xenon gas supports a high-current electrical arc to produce the
intense, white light used in the Model 220 projector.
First Condensing Lens (Asphere): The high intensity light output
from the Xenon Arc Lamp is picked up by the First Condensing
Lens (attached to the rear of the Arc Lamp housing) where the
light beam is condensed and directed toward the Cold Mirror/IR
Filter.
Cold Mirror/IR Filter: The Cold Mirror/IR Filter removes most of
the IR light and directs the light beam toward the Second
Condensing Lens.
Second Condensing Lens/UV Filter: Final condensing for the
light beam is provided by the Second Condensing Lens.
Ultraviolet light is filtered out by the UV Filter.
Diffuser: The Diffuser diffuses the light beam out more evenly
and reduces flicker.
2-4 Model 220 Service Manual