Boxoffice-January.08.1955

SERVICING
SOUND SYSTEMS
ntyne
f-Cone
luse
JND
antyne representnstrate
the Dub'lere
will you find
undistorted sound
at all volume
lOOF
n the speaker has
against moisture
i
1. Diaphragm is
:ect against dampce
coil is noncorjm—will
not buciwell.
)z. Alnico V mag-
-IREE to FIVE
power of earlier
erials.
B'L-CONE
ne super imposed
r with a 3 16-in.
;n for tonal resonxterior
cone prohe
interior cone
sound. Both are
/eatherproof. If
, you can replace
It in a matter of
purpose equipment
fw techniques
antyne
Co.
Omaha, Nebraska
Continued from page 43
and screwed down tight in order to insure
good electrical contact. A poor connection
will cause rioise in the system, in some
cases it ivill cause the loss of sound. Keep
oil off of wiring near the sound head, particularly
wires to exciter lamp and P.E.
in optical sound head.
cells
EASY
TO SERVICE
COMMENTS—The Motiograph S3 and
S4 systems are very simple to service, and
only a limited amount of test equipment
is necessary. With a good multimeter and
test loops you can do very satisfactory
maintenance. A complete set of tubes,
namely, on the A337A amplifier, tube complement:
three 12AY7, two 6L6G. and for
the A-338A amplifier, the same tube complement
with one more tube, 12AT7: the
PK)wer supply tube complement: three
5U4G. The small number of tubes promotes
ease and economy of maintenance,
and the employment of plug-in construction
so that each amplifier may be easily
removed or replaced makes easy servicing.
Most modern theatre amplifiers are now
being manufactured so that amplifiers can
be removed or replaced quickly. It is a
very good idea to keep a spare pre-amplifier
on hand, and a power amplifier, in
case of trouble. The defective one can be
repaired later. In a future issue, we will
present complete step-by-step data on
all leading amplifier circuits.
The servicing procedure of Motiograph
sound systems is no different than with
other makes. In case of a defective audio
stage, in some cases it can be located by
"circuit disturbance" test. Condensers
(capacitors^ , resistors and wiring should be
checked with your ohmmeter, checking tube
first, voltages next, etc., vmtil defective
part is located. Noise is caused by a
p)oorly made cormection, defective tube,
resistor, condenser—usually quickly found
if traced according to previous servicing
instructions given in this department. See
page 41. checking amplifier, Modern
Theatre, issue December 4, for simplified
servicing tips on checking audio amplifiers.
The same advice applies to this
.sound sy."rtem.
MODELS TO FIT ALL THEATRES
Motiograph manufactures several different
models of stereosound to fit the requirements
of any size theatre. Some time
ago we told you about its MA- 7505A amplifiers
for both stereosound and optic
sound reproduction which have been used
successfully in standard theatre sound
systems for many years. In the company's
slightly modified penthouse reproducer, a
few months ago, a few important improvements
were made in the case 'housingi and
wiring, otherwise it is the same sound head.
The changes made were the rounding off
of all the comers .so it will have a much
more attractive appearance and a few
Continued on following page
Drive-ln NOW
and let us
HELP
When it comes to drive-ins The Ballantyne
Company has always taken pride
in being more than just a manufacturer
of sound and projection equipment.
We feel that countless owners and
operators want help and advice on how
to build a better, more economical
drive-in.
That's why we offer these services.
If you have purchased land for a new
drive-in, just send us the general plan
and elevations. Without cost to you we
will lay out the entire theatre. If you
need plans for a projection booth, a
refreshment area or ticket entrance, as
illustrated above, we'll be glad to furnish
them without charge. And of
course, we furnish you with complete
wiring diagrams as well.
Now is not too soon to plan for next
season. Take just two minutes and
drop us a line if you're planning a new
drive-in. We'd like to help.
Originators of the complete pack'
age for ttie Drive-ln Theofres
'^Ballanti/ne(j&
1712 Jackson Street Omaha, Nebraska
\ars 8. 1955 47