58. Minor Adjustments
b. Lopsided Screen. The screen image will be lopsided when the
projector faces the screen a t a n a n g l e i n s t e a d o f s t r a i g h t o n . I f
the projector faces the screen squarely and the image still is lop-
sided, loosen the three screws that hold the front surface mirror
housing to the support arm, and shift the mirror housing to the left
or right until the top and bottom edges of the image are horizontal.
Then tighten the three screws.
c. Fit of Projection Head on Support Post. The fit of the projec-
tion head on the support post has been carefully adjusted at the
factory and should not be changed unless it is absolutely necessary.
If adjustment is required to prevent the projection head from moving
sideways, tighten the screws on the support-arm tube. The top and
bottom screws regulate the fit of the tube on the support post. The
two inner screws regulate the fit of the split portion of the tube against
59. Optical Alignment
a. Set the projector
up (par. 11) about
15 feet from the projection
screen so that the projector faces the screen squarely.
b. Turn the power switch to the ON position. Place a transpar-
ency on the projection stage and focus it as sharply as possible on the
screen. Then turn the power switch to the OFF position and remove
the transparency from the projection stage.
c. Open both the rear door of the projector housing and the lamp
house door. Loosen the projection-lamp socket clamping screw, and
move the socket carefully up or down until the center of the lamp
filament is in a direct line with the center of the condenser lens. Be
sure that the center of the eye, the center of the filament, and the center
of the condenser lens are in a straight line. Tighten the socket
d. Without closing the rear door or the lamp house door, turn the
power switch to the ON position again. Hold a sheet of white paper
against the bottom of the lens; be sure that the light reflected into
the lens from the projector housing is not obstructed by the hands.
Look in through the projection-head window, and observe whether or
not the octagon of light visible on the paper is centered with reference
to the lens.
(1) If there is a lateral displacement, loosen the support-post
clamping screw and loosen the support-post locating-plug
PH-637A/PFP). Hold the paper against the bottom of
t h e l e n s l i g h t , and move the projection-head assembly
to the left or right until the octagon of light visible on the