Technical information

O
RADIO
RETAILING'5
,,,
q\dee
BRUNSWICK
BRUNSWICK
ACIO.
Weak
signat,
all voltages
ok . Voice
coils
com-
monly
blow.
BRUNSWTCK
lt, t2,
15, 33
Weak
or no
reception
on low
fre-
quency
end
of
dial
look
for open
910 mmf.
condenser locatecl
betrveen
stator
of oscillator tuning
condenser and
high
side
of oscillator
plate
coil.
BRUNSWTCK
il, t2, t5, 23
Iiading, poor
selectititv or sensitivitv
.
Tighten
screq' f:rstening
10 ntmf
rrica
coupling
condenser to stator
sec-
tior-r
of
first dctector
corr<lenser.
BRUNSWICK
tl,
12, t6, 17,
lE,21, 25,
33.
Poor
volume
or
entirely
inopera-
tive
. .
. All models
use a screen supply
resistor
of 14,000
ohms, 2
watts,
fol-
lowed
by a l/3
watt, 5,000
ohm unit in
the
case
ot'the 24
oscitlator and another
l/3
watt, 5,000
ohm resistor
as
a
bleeder
to
ground.
These resistors
commonly
become
charred
and
their values
drop
to
as little
as 500 ohms,
or
they burn out
entirely.
Replace
thern with a 15,000
ohm,
2
watt
and
two
5,000
ohm,
j|
or
I
watt.
units.
No control
of volume
although
control itself
tests
ok
. .
.
Look
'for
grounded
grid
returns
in r.f., mixer
and
i.f.
stages. These
frequently
short
to hold-down
clamps, cutting
out
a.v.c.
and
manual
control
action.
(I.F.
175
kc.)
BRUNSWTCK
il,
t2
Shorted tuning condensers
caused
b1'
broken
porcelain
insulators
in turret
as-
senrbly use
fiber
insulators o[ the
same
thickness
for replacenrent.
BRUNSWICK u, 12, 16, 33, 24, 25.
Dial
slips To correct loosen and
remove
nut
above the center of
con-
denser assembly.
This
permits
retuoval
of the
planetary
dial arm. Looserr the
two screws
holding the tuning knob,
tone control and volunre assembly. Place
cardboard spacer
*
in. thick
underneath
the assembly
and
tighten again.
Replace
planetary
dial arnt.
BRUNSWICK
S1{.
Hum.
Look
for
Ioose
power
transformer laminations.
Number
of
laminations
in
60-cycle
job
varies. If
line ballast
tube
glows
slightly when
everything else checks ok
the core
is too small.
BRUNSWTCK
St.r
Noise ancl nrotcrboating r'eplace
grid
leads
frorn condenser statols
tc)
tube
grids,
incr'-a..e
tensiorr on
phono
srvitch
blades.
Dead
Inspect local
distance switch.
BRUNSWTCK
t5
Noisy,
change;
volume
re-
place
35,00O
ohm
screen
grid
resistor.
t4
BRUNSWICK
15.
Intermittent recep-
tion.
Check bypass condenser
just
be-
hind 45's
against back
wall of chassis,
down inside.
BRUNSWICK
15. Distortion
on all
stations,
reception
otherwise
ok. .
.
.
Chcck
detector
scrcen
by-pass.
This
often
shorts
out without
afretting
volt:
age
reedings
cnough to
notice. Check
the condenacr
with
t ncon lemp
to
be
sure
of it.
BRUNSWICK
r5. Full
reception
when
set
is first turne<l
on,
gradually
teding out.
Look for
open 25,000 ohrn
orange
resistor in scrden-grid
supply
circuit.
0luNswlcK
l5
Oscillation
open .l
mfd.
con-
denser
across speaker
socket.
This
condenser
in condenser
pack, green
leads.
lRuNswrcK t5
Squealing
. Usually
due
to
poot
contacts at
condenser rotor.
Contacts
tre
very ioaccessible.
Drill
a hole suf-
Eciently
large
to
pcrmit
inscrtion
of
a
screwdriver
through drum and chassis
in line with
the contacts.
BRUNSWTCK
t5-22
Signals
orrlv
at
high frequency
end
of dial
ofen prirnary
in
second
r.f.
transfornrer.
BRUNSWICK
15,22.
Noisy or in-
termittent
reception
. . . Check .02 mtd..
coupling condenser
in
a.f. circuit and
give
set thorough
mechanical inspection.
BRUNSWICK
lS, 22,
32.
Rushing
sound
like steam escaping,
particularly
noticeable
on lower end
of dial Re-
move shunt condenser
from
local-dis-
tance,
push-pull
tyne switch.
BRUNSWICK
t5,
22,
32,
42
Sudden
volunre
changes often
due to
loose
rivet holding
antenna
post
on insulating
strip. With local-dis-
tance srvitch in distance
position,
apply
ohnrnreter between
post
and chassis.
If
nreter needle
wavers,
replace
post.
Oscillation
bond
speaker
framq
to receiver
chassis
and make sure
set
has
good
outside
ground.
BRUNSWICK
rs, 22, 12. Noisy
volume
controls. Unsolder
the
pigtail
from
the second r.f.
variable
condenser
stator.
remove
the
rubber
sleeve
and
blow out the
powderlike
substance
found
in
it.
Wipe
powder
off
pigtail
and
re-
place
sleeve, resoldering.
BRUNSWICK.
Noisy and
irregular
reception
in certain models using
rub-
ber tube-covered
volume
controls .
.
Caused by dampness. Replacc
tubc
rvith
catheter
purchased
at
drug
store
if
duplicate tube is not
obtainable.
BRUItlSWICK
16. No
reception,
voltages
normal.
.. Oscillator
scre€n
resistor
has
probabty
changed value and
the
tube won't
oscillate. Replace
with
5,000 ohm
I
watt unit. The original
was
a
I
watt size. Distortion,
voltages
below
normal
. . . Check
same
resistor
for
abnormally
low
value,
practically
shorting
screen to
ground.
Inadequate
volume
.
Try
changing the screen
bleeder
resistor
from
14,000
to 10,000
or
7,500
ohms. Irading
or
abrupt
inter-
ruption of
reception, voltages
normal
.
. . Check
l0 mmf. coupling condenser
between
r.f.
tube and
6rst detector.
This
is mounted on bottom of
one
of
thc
turret condensers
with
a machinc screw.
The screw loosens and causes trouble.
BRUNSWICK
17.
No reccption
. . .
Check
for
grounding
of 14,000 ohm
screen
resistor at right
of chassis
be-
tween two coil shields, also
for .5 mfd.
condenser in oscillator
plate
circuit.
These
are common
faults.
ARUNSWICK {X}. Hum and reduced B
voltage. Either shorted
45
C
bias
re-
sistor or charred braided tubing
on
push-
pull
transformer leads to resistor
strips,
forming high resistance
shorts to chassis.
Lack of sensitivity. Fonnd
principally
in sets with serial
numbers
below 80,000,
especially those with brown crackle
finish.
Voltages check ok. Signal can
be built up by reducing scre€n
grid
cat-
hode 100
ohm
wire wound resistor to 25
or
50 ohms,
by heating
wax off
and
reversing r.f.
choke and antenna toading
coil leads to
position
of maximum signal
strength
or, by
re-aligning condenser
gang.
Motor-boating.
Caused
by opea
circuit in
small ,l
mfd, tubular condenser
fastened
to
targe
I
mfd. tubular con-
denser
mounted under r.f. section.
Open
circuited
l
mfd. unit causes
oscillation.
Well
over 50
per
cent of trouble in the
83 is
due to shorted or
grounded pig-
tailed carbon
resistors.
BRUNSWICK. Whcre scts having
limited output transformer space burn
these units
out
try a
G.E. output
unit.
Melt
it out
of
its can and insert it in
the original
container.
BUICK
1933 BUICK.
Brake static . .
.
Cotter
pin
in
front
wheels
is usually
loose. Place a lock washer under each
pin
to hold
them tight.
BUICK t30-,t873
Blows fuses
insulation on
shielded
grid
lead of
6RZ
worn tl.rrough
and contacting
filar-nent
prong.
CHEVROLET
CHEVROLET.
No signals
in
this
auto-radio,
all
voltages
and circuits
ok
.
Replace
small, blue Sprague
.002
condenser
across the
lower
end of the
voltage divider.
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