RCA
Loudspeaker
Model
100 Service
Notes
Non.-Cone assembly
of RCA
Loudspeaker
Model
102
is
identical to Model
.100
less
the
filter
unit
Prepared
by
NATIONAL
SERVICE
DIVISION
Instructions
NS -100.2
PART
I
RCA
Loudspeaker Model
100 is of
the
free floating
cone type. It is suspended
at
the outer
edge'by
means of a strip
of
soft
kid which holds
the cone in a
central position
but
does not impede
its movement
to
any great
degree. The
cone is attached
rigidly
to
the speaker mechanism
at
the
center.
In servicing
Model 100
Loudspeaker
always
make certain that
the output of
the
Radio Receiver
used
in conjunction
with it, is
of good quality.
If
distortion
is
present
in
the Radio Receiver,
RCA
Model
100 Loudspeaker
will
reproduce that distortion
as
faithfully as it does
the tone
variations of
the program.
Rattling
sounds,
or the
so-called
"paper
rattles," are generally
caused
by
a distor-
tion in the
lower tone
registers
of
the amplifying
system of the Radio
Receiver. It
is
therefore
quite important
to first
check
the
Receiver for quality
of signal.
This may
be done by
substituting
another
loudspeaker
of known
quality
or
else
by
replacing the
loudspeaker
with a pair
of
headphones.
If distortion is present
either in
the second
loudspeaker
or
the headphones
it is
a positive
indication that the trouble
is originat-
ing
in
the
Radio Receiver.
Similarly, if
the Radiotrons
in
the
Receiver are overloaded
by an abnormally
strong
signal being
forced through
the
amplifiers,
distortion
will follow.
If it is definitely
established,
however,
that the distortion
or rattle complained of
is
not due
to a defect
or improper
adjustment
of the Radio Receiver, but is
apparently
caused
by
the
Loudspeaker
itself, it
may
be
the result
of
one
of the following
conditions:
(A)
Foreign
material interfering
with armature
vibration.
(B) Armature
striking
the
pole piece.
(C)
Cone
misaligned.
(D) Excessive
pressure
on the stylus.
(E)
Bent stylus.
(F)
Loose or
bent
connecting
rod.
Figure
1 shows
a rough
sketch
of the complete
armature assembly and
its relation
to the
cone.
The armature
vibrates between
the
pole pieces
(not
shown), this motion
being
transmitted
through
the
stylus to
the thrust lever.
The thrust lever is held rigidly
to one
of the
motor side pieces.
It is attached
rigidly
to the
cone
by
the connecting rod.
Dirt
at any
of these points
may
cause distortion.
On
inspecting
the RCA
Model 100
Loudspeaker,
note
whether or not the stylus
is
bent, if so
straighten
it. The
cone is
attached to
the connecting rod
by means of a small
nut
"B",
Figure
1. The
end
of
the
connecting
rod
is threaded. Make
certain
that
the
cone is
drawn
up tight to
the
connecting
rod.
If the
two foregoing points
have
been
checked and found to
be
O.K., note
whether or
not the
armature is
striking
the pole
pieces.
Figure la and Figure 2 show the relation
of the armature
to the pole
pieces.
There
should be
a space approximately
.010 inch
Between the armature
and
the pole
pieces,
Figure
la.
This
is
true at both
ends of the
armature.
3
www.americanradiohistory.com
To Next Page
Need help?
General
