Boxoffice-November.24.1951

PROJECTION AND SOUND
Here Is
How to Check the Equipment
WHEN TROUBLE STRIKES
IN
YOUR BOOTH
riow WELL DO YOU know your equipment?
Do you know where the fuses are
located—how to quickly check for trouble
in the amplifier, speakers—sound lens setting—speed
of projector, etc? Knowing
your equipment is very important if you
want good results. I cannot too strongly
emphasize that every projectionist should
be thoroughly acquainted with all the
equipment under his control. A block diagram
is necessary for quick checking of any
sound system for trouble. It is best to establish
a systematic routine when searching
for trouble. First, know where all your
fuses for the amplifier, projection room.
by WESLEY TROUT^
poor contact or dirty contact. Let us next
check all the connections from soundhead
to amplifier to be sure they are okay. Keep
wiring clean and connection tight. Did you
(Continued on the next pagei
Trouble in the Soundhead?
Here's What to Do:
1. Trouble in the soundhead is sometimes due to
a defective P. E. cell, exciter lamp out of focus, dirt
or oil on the sound lens, exciter lamp not burning or
filament sagging. Check P.E. cell voltage. Keep all
connections tight and free of oil.
2. The next unit is the pre-amplifier. See if input
tube or tubes are okay. Most of the modern amplifiers
have meters and you can quickly tell if a circuit
is all right, but check tubes as explained in the
accompanying article.
3. Check the power unit of the amplifier, tubes,
connections, resistors, condensers and see it tubes
check okay and voltages ore correct.
The next check is bock stage where the speakers
are, if everything is oil right in the projection booth.
Your trouble there might be in the crossover box,
poor connection, defective speaker field, etc.
rectifiers or motor generator set are lo-
Let us check first and see if the exciter
lamps are lit. Remove film and check, with
small white card, if light is coming through
Systematic checking is the quick way (o locate
trouble, and the units to check, as indicated in the
above photograph, arc the soundhead, the preamplifier
and the amplifier power unit. If all of these
arc all right, the next check is on speaker lines and
speakers. The above booth, with Motiograph pro-
"Engineer-Manager, Convonlion Hall, Enid, Okla.
cated. If the sound system suddenly goes
dead, check the fuses; the same, if the
rectifiers or generator set quits. If your
power is okay to whatever equipment goes
dead, then the trouble boils down to locating
the unit in which the defect exists.
sound lense to the P.E. cell. This double
checks the exciter lamp for correct alignment
and .shows if there is any obstruction
cutting light, or part of it, off. Now operate
fader or changeover switch several
times in order to eliminate any possible
check P.E. cell voltage? Now if you find
everything okay with the soundhead, let's
check the amplifier. Turn up the volume
lecton, located in the Ross Theatre, Evansville, Ind.,
A
background
of varied experience
in the theatre
business particulary
in projection
qualifies
Wesley Trout to
write with authority
on solutions
to the
problems that
beset the man in the booth.
His show
business days date back 25 years to
Clinton, Okla., where he managed a
theatre. In addition, his experience includes
projection, ushering, advertising
and publicity and management. He
has authored several books on servicing
equipment, including sound. His
articles on projection and/or sound
will appear in regular issues of the
Modern Theatre Section of Boxoffice.
is exceptionally well laid out. Note the fire shutters
are fused, and all connected on one master pipe, the
observation ports are of ample size, the projection
ports are standard size with glass to keep noise out
of the auditorium. Under each lamphouse is a container
for carbon stubs, and changeover switches are
ideally located on the base of the projector pedestal.
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68
The MODERN THEATRE SECTION
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