Technical information

;
RADIo
RETAtLtNG's
rr,
eh.n@
COLONIAL
C-995.
A
hi-lo sensi-
tivity
switch,
which will
cut down'inter-
station
noise
when
tuning
locals
with
this
a.v.c.
model, may be
added by
re-
moving
wire
lead betwecn
lugs 1 and
2
of
the Candohm
reststors,
connecting
a
100 ohm
type between
the
lugs, cutting
the
ground
connection
to
lug
I and
gounding
lug
2.
Drill a
hole in the
right
side
of the
cabinet
to receive
a
swltch
and
connect
the switch
across
tho new
100
ohm
resistor so that
it
may
be
cither
shorted
out or
placed
in
the
circuit.
COLUMBIA
COLUMBIA
SG{
Oscillation
when volume control
is
advanced .
insert
a 5000 ohm
re-
sistor
in
the
grid
circuit
of
the
detector.
COLUMBIA
C2
Intermittent
frying noise
.
. .
usually
caused by
defective
insulation between
prirnary and
secondary of
the
r.f
coils.
Very often
a small
amount
of
rnoisture
in the
coils
will
cause
a similar
trou-
ble.
Dry the set
out
thoroughlY
bY
placing near a
source
of heat
for
a
few
hours.
COLUMBIA
C.8OA.
Distortion
.
..
check
au<lio
coupling
cortdt'nser
t'ttcl,tst'tl
iil
capxc;t'r
case
mountecl above chassis.
Also check
grid
coupling
resistot'
of
'17
rvhich
has
tend-
ency
to change
valuc.
Correct
resistatlce
is
300,000
ohms.
coLuMElA
c-t0l
Distortiou
RePlace
'10,000
ohm
l
watt
resistor in
cathode
circuit
of
de-
tector.
The
original
resistor
has
changed
to
high
value.
Resistor
is
located
under
a triple
bank of
coils.
COLUMBIA
CsOOA
Oscillation.
.
.' Check
spray
shield
on
tubes
for
contact
rvith
base
prongs'
CORONADO
coRoNADO
650
Intern-rittent
one or
both of
the two srvitches
nrounted on back of
'r'olunre
contt'ol
is
tlef,
clivt'.
CORONADO
AUTO
SET
Buzzes
and
crackles
Poor
in-
ternal
conection
in
buffer
condenser'
Iteplace
with
new .01
m{d.
1600
volt
rrrrit
sol,lered
across
plates
of
the
84'
Buzzing
m:ty
also be
due
to
open
-qrld
return
6lter
1n
output
tube
circuit.
Con-
rrect
.25
nrfd.
condenser
between
junc-
tion
of
two
grid
resistors
arlcl
gro.und'
'l'his
orocedur"e
eliminates
vibrator
ripple
front
the
bias
voltagt:.
(Jotltletrscl
ntay
lrc low
voltage
tYPe.
l6
CROSLEY
CROSLEY
5M3
Dead
slrorted
sectioti of
electlo-
lr-tic
conclenser
in
catt
above
chassis.
CROSLEY 6H2
Cuts
out on
weak stations
lower section
of
25,000 ohnr
bleedcr
rcsistor
open.
CROSLEY
7,
10. fube
hiss
. .
Cort-
nect 2 or
3 nreg.
resistor
in series
with
screen
of
first
detector
58, bypassittg
v"'ith
400
volt,
.01 condenser.
For
better
high-frequency
audio
resporrse
. . .
Clip
one
lead
of dual
condenser
used
iu tone
control circuit.
On
dual
l0 clip
tirrrrctl
rvire coming
out
of
end
of cottdettscr
nearest tone
control.
On
dual
7
clilr
trrrned
bare
wire
from
end of
cotlderrser
to
plate
of
2A5.
This does
not affect
tone co:rtrol
ol)eratloll.
CROSLEY
7H2
Poor rcception,
volutne
c<-rntrol
does
rrot oper:tle
properll open section
of
Llandohm
resistor.
This
is the
11,000
ohrn scr:tion
coltnected
frotn
screens to
ground.
CROSLEY
7H3
Motorboating.
.
Frequentlycaused
by high-resistance
ground
connection
in
the
shielded
wire
going
to
the
grid
cap
of the 687.
cRosrEY
8Hl
Excessive
hissing
.
between
stations
. .
. Change
6F7 cathode
resistor,
a
snrall,
flexible type
mounted on
the back
of
the chassis,
from 500 to
250 ohms.
Also.
shunt
a
2.0ffi
ohm resistor
acrost
the cathode
bias
resistor of
the 6D6,
nearest
the
por,r'er
transformer.
CROSLEY 8Hl.
Common
trouble
.
Balancing condensers
located
on
top of i.f. coil cans short
out to
mount-
inr
screws,
due to
plates
of condensers
being
out.
of
line.
Thus, when
moved
out of their original
position
they touch
the
grounded
mounting
pillars.
CROSLEY
27,28.
No recePtiotr,
weak signals
or
intermittent
reception
. Check
for faulty
I
mike bypass
con-
nected betweeu
s-g
of
32 detector and
ground, It is in a can,
with two ter-
nrinals
exposed.
Each terminal
is a
separate
condenser
with
the
cottlmon
counection to
grpund.
CROSLEY
30S. Failure
of
rePlace-
ment
volume
control
to
permit
reduction
o{
level
to minimum
requircd
. Short
3,500
ohm
resistor, in
series
with
the
control,
conrpletely
out of the
circuit.
CROSLEY
30S,
3lS,
33S.
ImProving
.volume
and
tone
. . . Put
a 15,000 ohnt
resistor
between
positive
side of the
55,-
000 ohm detector
plate
resistor
and
groutrd.
CROSLEY30S,31S,33S,34S.
Com-
mon trouble
which should
be checked
before wasting
time on
analysis .
.
.
Sockets
readily short
to chassis as
holes
in
chassis
admitting them
are
too
small
for safety.
cRosLEY
30S,
3tS,
33S.
3{S
Apparent
shortcd
coupling
condenser
.
..
.Check
sdcket
prongs
.to
ground.
Lhassls
socket
holcs
sometimes
are
too
small
to clear
prongs.
CROSLEY 405.
VI/hen
tone
is
bad,
pep
Iacking
ond an atnlyzer
chech shozas
poi-
titte
bias
on the
first
gudio
tube, replace
thc by-pass
condenser
connzcted betu,eet
the detector and the
fir.ct
audio
orid.
CROSLEY
,T'S
Noisy
and
distortion
at
high vol-
ume
. . replace
440
resistor
under
chassis.'
Check
first
r.f. coil
for
inter-
nrittent
short.
CROSLEY42S.
Over-sensitivitv
5,500 ohm
bleeder frequently
op.nr,
raising
all
voltages.
CROSLEY
42S.
I-ou' bias voltage
on the detector, distortion
Fre-
quently
due to
leakage between sections
of the
dual
.5 condenser by
passing
de-
tector and
first a.f. bias resistor.
CROSLEY '2
Insensitive, low
volume replace
large
6000 ohnr
carbon
resistor rr'ith
t'ire
rvound l0 watt
unit.
The value
of
the original
resistor
has increased
greatly
due
to overload.
cRosLEY
42-s
Low volume,
troisl'
reception
bot-
tom
plate
of
chassis
touchirlg
centel'
tel'-
rninal
o{
volutne
control.
(ilue
:r
piece
of
insulating
material
to the
platc
to
prc-
vcnt contact.
CROSLEY
53,
5'1,
57.
Noise
and
dis-
tortion,
sounding
like defective
speaker.
Look for
trouble
in
coupling
condenser
between
detector
plate
and
45
grid.
Re-
place
with unit
which
will withstand
300
volts.
CROSLEY 54
Opening
of
heavy duty
resistor
in
"B"
supply
network
is most conlrnon
tlouble.
If
set
whistles,
look
{or
de-
icctive'r'olurne
cotrtrol.
CROSLEY
5E, 59.
Hum, not traceable
to filter troubte . . .
Replace I
megohm
resistor
in 47
grid
circuit,
connecting to
high-voltage
secondary tap.
C
c
t
I
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