Boxoffice-May.03.1952

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PROJECTION AND SOUND
Change Your Oil Mr.
Projectionist?
The Best Advice Is to Change Every 200 Hours,
And Stay Away From Off-Brand, Cheaper Grades
by WESLEY TROUT Wesley Trout
I ODAY S MODERN PROJECTOR IS a Very
expensive piece of equipment. It is built
with precision tools by skilled mechanics,
and with proper care and maintenance will
give years of fine service. You can secure
long service if you use the right lubrication,
install parts when needed, and follow the
manufacturer's recommendations as he is
vitally interested in seeing that his equipment
operates satisfactorily. Most projector
manufacturers sell oil which they recommend
for use on their mechanisms; supply
dealers distribute only the very finest projector
oil. and I strongly recommend that
you use it and not a cheap grade of lubricant.
OIL MUST BE RENEWED
The intermittent movement is subject to
very heavy service and a "special" oil
should be used for most satisfactory service.
Here again I urge that you purchase
only the lubricant recommended by the
manufacturer, purchasing it from your
local supply dealer. Oil becomes "poor"
from continued use and should be renewed
in the intermittent every 200 hours. Take
the intermittent out of the mechanism and
empty the old oil out and refill with new,
clean oil.
As you probably know, oil loses its
lubricating powers after so long and
then your parts start wearing out unnecessarily.
Bear in mind that the intermittent
sprocket starts and stops 24 times a second.
This high speed of your intermittent
sprocket requires fine, precision parts which
your manufacturer gives you in today's fine
projector. You can readily understand why
it requires good care and the tmst in lubrication.
This advice applies to your entire
projector lubrication.
USE
RECOMMENDED OIL
Only lubrication lecommended by the
manufacturer or serviceman should be
used to lubricate your soundheads. Never,
never use graphite, or anything else except
pure oil for your projector or soundheads.
One or two drops of oil is plenty in any
bearing, too much oil simply runs out of
the bearing and gets on the film.
Modern mechanisms that have all the
gears running in oil in an oil-tight gear
compartment: the oil should be completely
drained out by opening the drain petcock,
making sure that no foreign material remains
to interfere with the gear operation.
Always thoroughly clean inside with a soft,
clean, lintless cloth before replacing gear
compartment cover. My experience in oil
changing has thoroughly convinced me that
oil in these compartments should be
changed every 600 to 700 operating hours
for best results. I al.so am convinced that
the oil in the intermittent should be completely
changed every 200 hours to achieve
the finest operation.
NOTE: The mechanism of any projector
should not be cleaned when, it is running.
If this procedure is not adhered to damage
may result by the projectionist getting the
cleaning rag caught between the gears or
tangled betioeen the shutters and the shutter
housing.
KEEP
ALL THE SPROCKETS CLEAN
It is of paramount importance that you
keep the intermittent sprocket perfectly
clean at all times, because any dirt that
accumulates on the sprocket teeth will
cause an unsteady picture on the
screen. I suggest that you use a stiff bristle
toothbrush and brush all the sprockets
every day, moistening the toothbrush with
a little chemically pure carbon tetrachloride.
You should clean and thoroughly
examine all your sprockets every day, and
if you find any that have become "undercut,"
replace immediately. "Undercut" and
dirty sprockets will cause picture jump and
film damage. Check your sprockets and see
that they are in perfect alignment so that
the film travel is straight from the top
magazine to the lower magazine. See that
all idle rollers run freely and do not develop
flat places. The correct distance of
sprocket idlers from the face of the sprocket
is the thickness of just little more than the
film, any more than this is bad, and the
idler should never "ride" the sprocket face.
I always place two thicknesses of film on
the sprocket, and adjust idler so it just sets
on film.
EMERGENCY EXCITER LAMP SUPPLY
If your exciter lamp supply is AC and
the transformer that supplies the correct
voltage suddenly goes bad, you can use an
ordinary 500-watt electric heater element
which is wired in series with the exciter
lamp and the regular 110-volt AC current.
This can also be used for emergency setup
with DC power units, and will work very
well until you can make a permanent repair.
Modern soundheads are well built and
rugged in construction, but they are a
delicate piece of machinery and require
careful maintenance so that they will give
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satisfactory sound reproduction. The P.E,
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cell should be kept clean and the correct
voltage maintained as recommended by the
manufacturer. Keep in mind that it should
be properly lubricated, the stabilizer drum i
free of dirt and revolving freely in order
to avoid flutter. The guide rollers i
must
be accurately adjusted and turn freely so
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as to avoid grooves in sides.
TAKE TIME TO FOCUS EXCITER LAMP
Sometimes too little attention is given
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to focusing the exciter lamp. Take time i
and focus exciter lamp so that you secure
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clear, white oval light on a card placed
in front of the P.E. cell. If you want a
perfect setting of exciter lamp, connect an i
output meter to the terminals of the loud
speaker circuit and thread in projector a
7,000 c.p.s. loop, and adjust exciter lamps !
until you have secured maximum volume on
the meter. As you probably know, an output
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meter reads sound volume in decibels which
is the unit for measuring sound increases.
A small output meter is very handy and :
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can be purchased at a very reasonable
price. Be sure to clean sound lens with
tissue when setting exciter lamp or focusing
sound lens.
Loss of frequencies is usually due to oil
on sound lens, darkened exciter lamp, im-
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properly focused exciter lamp on sound
lens and defective P.E. cell. If oil has
seeped into the lens tube it is best to
secure a loan lens and return the defective
one to the factory.
SOUND TRACK MUST BE SMOOTH
The sound track moving past the lightslit
of the sound lens must be absolutely
smooth in order to avoid "flutter." This
means that the sound drum or stabilizer
should be kept in perfect condition and
free of any dirt accumulations. The sound
head sprockets should not be "undercut,"
The film must be held in place perfectly by
the lateral guides so that its downward
travel will be straight and the light beam
will not strike sprocket holes causing a
loud hum known as "motor-boating." The
entire drive mechanism should be chfecked
regularly and screws checked for tightness.
NOTE: Every day check drum, pad or
gate and remove any particles of film wax,
oil or lint. Any foreign matter that might
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40 The MODERN THEATRE SECTION