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Chapter 4---Optical
Model 250 Service Manual 4-3
CAUTION
!
Fan disconnection is acceptable for a short
period of time only (preferably <20 minutes--maximum 45 minutes).
WARNING!!!
Dangerous levels of ultraviolet and
infrared radiation, dangerous glare, very high temperatures (180°C to
300°C) and high internal gas pressure are present at the Xenon Arc
Lamp. Protect eyes from ultra violet light and infrared light by using X5
(375 to 700 nanometers), ANSI approved, shade goggles when
actually working on the projector near the arc lamp source.
6. Access the "Shutters on Hide" box again from the System-Preferences
menu and uncheck the box, then use the RGB and HIDE keys to hide
Green. This mutes video from the Green CRT but leaves the Green shutter
open to allow Arc Lamp light from the Green ILA
®
to display on the
screen.
7. Select ILA
®
Bias from the System-Factory Adjustments menu. Record the
current ILA
®
bias level. Return to this bias level when this adjustment is
complete. Record only the Green ILA
®
bias value because Red and Blue
will return to their original levels when Green is reset.
8. Use the up-arrow key and adjust the ILA
®
bias for Green for maximum
light output.
9. Adjust the Arc Lamp alignment screws (see Figure 4-2) to center the "hot
spot" (brightest area). Figure 4-1 illustrates a "hot spot" on the screen.
NOTE:
It is easier to perform the following procedure with one person
standing in front of the screen holding a light meter and another person
making the adjustments to the Arc Lamp.
10. Use the light meter to locate the brightest area or “hot spot”, (see Figure
4-1). Move the light meter around the screen to determine where the hot
spot is located. The “hot spot” will be where the light reading is highest.
11. Adjust screw 1, 2, or 3, (see Figure 4-2) to move the hot spot to the center
of the screen. Moving the “hot spot” will generally require adjusting two
or more screws. Adjusting all three screws adjusts the Arc Lamp on the z-
axis. Adjusting the three screws clockwise increases light output and
rolloff.
12. Check for maximum brightness and readjust the z-axis as necessary after
setting the x-axis and again after setting the y-axis.
13. Tighten spider lock down bolt.