RCA 100 - Page 9

Telephone
Tips
CONTINUITY
DIAGRAM
MODEL 100
LOUD
SPEAKER
FIG.
16
PART IV
Continuity
and Filter Tests
Coils of
Reproducer
Unit
There are two
types
of filters appearing in the Model
100 Loudspeaker,
one con-
tained
in a
cylinder
and the other in a square box.
Both of these filters
are electrically
identical,
the only
difference
being in the
type
of container employed.
In
the model employing the cylindrical
type
of filter (Fig.
14)
the
input leads
(phone tips) are connected to the two
binding
posts at
A and B on
the
frame.
In the
square filter type (Fig. 15), however, one of
the phone tips
is soldered
to
point A and
taped, the other being
connected
to
the
binding
post at B.
The only equipment required
to test
the
electrical
circuit of Model 100 Loudspeaker
is
a pair
of head
phones
connected in series with
a
41/2 -volt
C
battery. The test
points
are
shown in
capital letters in the circuit diagram
and
illustrations, Figs. 14, 15 and 16.
Before starting
the
"click"
test, disconnect
terminal
D from the binding post at
B.
This
free
terminal D
will
then become a separate test
point.
In case terminal
A
is
a
taped connection, as it is in the sqúare
box
filter type of Model 100 Loudspeaker,
the
tape will have to be temporarily removed
to
expose the metallic surface for
the
"click"
test.
Remove loudspeaker plug
from
radio receiver jack
before
proceeding with test.
CONTACT POINTS
A
to
D
AtoC
C to D
C to B
CORRECT
EFFECT
Click,
closed
thru filter
coil
and reproducer coi
Click,
closed thru filter
coil.
Click, closed thru
reproducer
coils.
No click,
open thru filter condenser.
A to B No
click,
open
thru filter coil
and condenser.
DE.EECT
ls. Open in
circuit.
Open filter coil.
Open reproducer coil.
Filter condenser or
tele-
phone plug
shorted.
Filter condenser or tele-
phone plug
shorted.
NOTE.-Care
should
be taken to
replace
terminal
D
on binding
post at B
after
completion
of "click" test.
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