Bell & Howell - Projector - Filmosound 641 - 642 ... - Cine Information

sprocket hole will register exactly
with the end of the rule.
(5) If the leading edge of the last
sprocket hole registers with the
end of the rule, the film has
approximately 0.4% shrinkage.
Since the variation is usually
linear, a film which had shrunk
half the height of a sprocket hole
would have approximately 0.2%
shrinkage.
(6) If the trailing edge of the last
sprocket hole overshoots the end
of the rule, the film is stretched.
Generally you will find that the
film will have some shrinkage.
If the film is shrunk more than
0.5% (height of 1-1/4 sprocket
holes), do not use for adjustments.
B. Adjustments (See Figure 11)
(1) Loosen the retaining screw (5)
and rotate the adjusting cam (6) so
that the end of cam follower (11)
clears the end of the restorer
cam by approximately 0.015 inch.
Note - If the cam follower strikes casting
before proper clearance is obtained, move
the cam away from the casting.
(2) Thread the projector with film of
known shrinkage. Turn framer
to the maximum counterclockwise
position. Turn the mechanism by
hand until the shuttle has engaged
perforations at top of the stroke
but the stroke has not begun.
(3) Loosen the screw (8) which holds
the cam follower support bracket
(12) to shaft.
(4) Position the loop restorer (13)
as follows:
(a) Film shrinkage 0 to 0.2%; set
restorer 0.015 to 0.020 inch
above loop.
39
(b) Film shrinkage 0.2% to 0.5%:
set restorer 0.010 to 0.012
inch above loop.
(5) After establishing the correct
clearance, tighten the screw (8)
securely.
(6) Turn the mechanism by hand until
the lobe of the restorer cam is on
top dead-centre.
(7) Push the cam follower (11) forward
until it passes under the
cam. If the end of the follower
does not clear the cam by 0.018
to 0.020 inch, loosen the two
screws (9) and move the follower
downward to establish the correct
clearance.
(8) Turn the mechanism by hand until
the shuttle reaches the end of
stroke. Open the gate and pull
out the loop.
(9) Hold the film lightly against the
aperture and turn the mechanism
to restore the loop. Observe the
shuttle teeth as they re-enter the
perforations. Adjust as follows:
(a) If the bottom edge of the shuttle
teeth does not clear the
bottom edge of the sprocket
holes, move the cam follower
upward.
(b) If the top edge of the shuttle
teeth does not clear the top
edge of sprocket holes, move
the cam follower downward.
(10) Run the projector and check the
operation either by pulling out the
lower loop or opening and closing
the gate. After the loop has been
restored, place the tip of finger
on the top of the restorer and
check for pulse at loop frequency.
If a pulse is detected, increase
the restorer clearance as instructed
in Step (4) (a), preceding.