Technical information

O
RADIO RETAILING'S
"Setuie
BOP
CHEVROLTT. Pronounced
vibntor
bvzz . .. Removc
75
tube. If
troise
ltops rcplece tubc
end
rhort
scrcw-
driver
ecrou
grid
to
ground.
If buzz
continucr
cqurlly toud
ptece
tl
mike
con-
denser ecrogs
B
ptur
to
ground.
Troublc
ir due to
opening up
of 6ltcr
output
condenscr.
CHEVROLET.
Intermittent
spark
noise, not
traceable
to
faulty
supprcs-
sion . . . After
a
year
or so in
use, es-
pecially
in l93l
and 1932 models,
the
bcading along
the
top
pulls
away where
thc side
beading
connects
with
the
bead-
ing across
the front.
Electricalty
makc
a
good
connection
between
the
open
cnds with
a
piece
of
copper
braid and
ground
to
the top
of the
door
post
on
cach side
of
the car.
This should
be
tricd
when noise
disappears
with the
an-
tenna disconnccted,
domc
light is
cut
loose and
antenna
shield is
well
gtounded
to
the instrument
panel
bolt.
CHEVROLET
36{{{l
(1933).
Qs-
cillator
dead
on
all
or
part
of dial . . .
First
section
of
candohm
strip,
4,200
ohms,. .002
condenser
across this
re-
sistor
and tube
all
ok. Replace
oscil-
lator
coil even
though
continuity
test
reads
perfect.
CHEVROLET 600{9.
Severc chas-
sis
pickup
of noise . .
. See
if
the
ground
lcad
is connected
to the lighting switch.
If so
move
it to
one
of
the door
jamb
bolts, or
bond
the dash to the door
jamb
bolts and to the fire wall with
heavy
conductor. The
dash is
generally
a
poor ground
without this bonding.
CHEVROLET
60I038
Intermittent
replace
30,000 ohm
screen
grid
dropping
resistor (R2)
CHEVROLET 1929,30,
3r, 32.
Ob-
stinate
cases
of
ignition
interference
.
.
.
Bond
the body
to the frame,
or
chassis,
at both sides, in
the front.
Right
about at
the
bulkhead
is a
good
spot to
do this. This
is
particularly
effective
when
the car has
run up
a lot
of mite-
agc.
Use
a
piece
of heavy
shielding and
self-tapping
screws
both in
body
and in
frame.
In
extreme
cases
of noise
nrove
the
electrolock
cable
and wire
up iC-
nition
like
later
model.
with
one switch
in
hot lead.
CHEVROLET
'33.
Noise,
when
passenger
is
seated
in front
Place
shield
plate
of
tin
beneath
floor
boards
where
feet
rest
and
ground.
f933
CHEVROLET.
To completely
eliminate
generator
interference
Connect
condenser
to second 6eld wire
of
the
generator.
Stop-light noise
Bridge switch with
a I
mfd.
condenser,
connccting from
terminal
to terminal
.in-
stead of from
terminal to
ground,
the
usual method.
CHRYSLER
CHRYSLER
'AIRFLOW."
Fail-
ure to
find built-in
antenna
lead
. .
It is
brought down the
right
front
corner
post,
as
usuat,
but is then carried
several inches
farther,
down
toward
the
floor inside
the
post
and then
brought
out. Necessary to remove screws
hold-
ing leatherette covering
post,
reaching
behind
it
for wire. Sets
are easily
mounted on upper
part
of butkhead.
Care
should be taken that
mounting
bolts do
not
extend over
one-half inch
beyond engine side of
firewall as this
will
prevent
opening
and closing of
hood.
In most cases
no bond betweerr
motor block and
frame is necessary.
Shield antenna
lead up to
I inch within
corner
post.
CHRYSLER. Static discharge due
to drag
emergcncy brake
on driveshaft,
occurring
whenever
motor is not actu-
ally driving thc car .
Mount
holder
for
small carbon brush so that it makes
contact with
the
emergency brake
drums, insert
a brush
and
ground
the
holder.
CLARION
CLARION AC
5I
Low
volume,
lorv voltage
.
. .
Check
I nrfd.
condenser
across
900
ohnt out-
pnt
bias resistor
for short.
CLARION
60
Inoperative
or noisy
check for
open in input
audio transformer. This
is
a special
transformer
and must be
replaced
with
original
unit
for original
tone
qualities.
Resistance
coupling may
be substituted.
clARtoN
80
Inoperativc,
260
olrrrr rcsistor
he:rt-
ing
test rccl lcarl
to
'bvDass
con-
clenser
block
for
short.
CLARION I60
Intermittent leception
Check
.00005
mfd mica condcnsel
in the
grirl
circrrit
of
the oscillator'.
CLARION
AC-t60
Volunre controi inoperative
. .
. Check
.35 nr f d
conclenscr ir.r
plate
circuit
of
secorrcl detector.
Replace with
.1
n.ifd
600 volt
unit.
CLARION
340
Cuts
off abluptlv
torvarcl
600
kc.
enrl
of
clial. Replacc'
8000
ohur
bias
rc-
sistor
on 57 oscillrttor
n ith
6000.
CLARION
470
Distortion,
lorv
sensitivity .
. . change
5,000
ohm bias resistor
on 2A6
to
10,000
ohms.
CLARION 480
Weak, distortion,
tunalite actiorr
poor.
Excessive
bias
on 56 first
audio.
COLONIAL
coloNtAL
3tAC.
Set
dead,
no bias
on r.f.
tubes
cven
tliough
bias resistor
checks
ok
Diagram
shows
r.f. filament
winding
in
power
transfornrer
as
being
center
tapped.
Actually,
a
center
tap wire
lvound
resistor
is
sealed
in
the trans-
folnrer
case
and these
open
up. Re-
pl:tce
witir
an
external
l0
or 20
ohm
centcr
tapped resistor
nrounterl
olt
trans-
forrner
ternrinals.
COLONIAL
3l DC.
Set
plays
with
switch
oft. Disconnect
ground
lead.
If
set
cuts out trouble
is
shorted
condenser
in
series with
this
lead.
It
is
onc
of
three
capacities
at
left
of chassis
when
set
is
turned
upside
down
on bench
with
hack
of set forward.
COLONIAL
32AC
Oscillation,
instability
on
high fre-
quencies
open
35,000
ohm
carbon
resistor (pink)
from
screen
of first
r.f.
to chassis.
COLONIAL
32.
Loss
of tolunc
ac-
comltanied
by
poor
tonc
is risually
due
to
an ofctt
frst
audio
ltias
rcsistor.
7'htsc
are
,ol
tht
flexiblc
tl,lte
and
brcaks
gut-
cratty
occur
rvar
cithcr
cnd.
Ilnztind
a
Iezu
turns
ol
rcsistoncc
ztirc lo
.ttt
drtt
thc
breah
and
.tasoldcr.
COLONIAL
32AC
Distortion
at
high
voluure
.
defec-
tive
100,000
ohnr resistor
between
cen-
ter-top of input
transfornrer
arrcl
ground.
coLoNtAL 33-3{
Intermittent
.
. .
shorted
or
broken
phono
switch
controlled
by
tuning
con-
denser, replace.
COLONIAL
35
AC. Failure
of
this
model to tune
betueen
550 and 500
kc. is
due to
shorting
out of the
phono
suitch
byt
the
dial
itself.
Loosen
the
nuts holding
the
szdtclt ond
prsh
it
farther
back.
COLONlAL
EI
No reception
Remove
speaker
plug
from
chassis
and
test
for con-
tinuity
between
two
smdler
prongs.
These
are
the
primary
lead
of
tfie onrtput
transformer
which.is
subject
to
burnout
due to
heavy
current
of
parallel
47's.
COLONIAL
600A
fntermittent
lead
of
6,47
. replace
solid
grid
flexi'ble
wire.
1933
CHEVROLET.
Remove
ignition
coil
from
bulkhead
and
fasten
to"motor
using
valve
inspection plate
bolt,
'33
CHEVROLET.
Noise,
disap-
pearing
when
antenna is
disconnected
from
set
Generally
picked
up by
shielded
antenna lead
which runs
be-
hind
instrument
panel
and is frequently
in
indu611t.
field
of cable running
from
key
to coil. Run
antenna
lead at
right
angles.
15