Technical information

A
RADIO
RETAITING'S
",
e)'de
cRosLEY A-r57..
Set stops
playing
when
jarred
install
new
tube
socket for
the 6A8G
as
original unit
does
not grip
the
prongs
tightly
enough.
CROSLEY 158.
Local
stations barely
audible rvith
volunre on full Look
for open 750 ohrn resistor
connecte<l
frorn
grid
of
58 to
ground.
CROSLEY 160.
Poor
tone and lack
of
volume .
See
if
59's are matched. If
trouble
is experienced in
matching
push-
pull
stage
plate
currents
connect
a
100
ohm,
I
watt
resistor,
preferably
non-iu-
ductive, in
series with
each control-grid
right
at the sockets.
CROSLEY
I60
Weak replace
the
20,000 ohnr
oscillator cathode resistor with
5,000
ohms.
CROSLEY
163
Bad
distortion
after
.set
wirrurs
up
.
replace
1.50,0()0
ohnt
resistor
in
the
cathocle
circuit
of
the 77 with
100.000.
CROSLEY
f67.
Low
volume
and
distortion . Frequently
traceable to
leak between filter
condensers
and
cathode by-pass
section for
the
2A5.
CROSLEY 167.
Set
rr.orks
9n
high
freqrrency
end
but
dies
out
on iow.
-or
cuts in
arrd
out . . .
The
.1 rnfd.
con-
denser across
the
3,500 ohrn
resistor
in
the cathode
circuit
of
the first
58,
the
first detector-oscillator,
shorts
out
and
sometirrres
partly
shorts
CROSLEY I67
Oscillation all over dial rvhen
vol-
ume is turned
on
full,
noise like fog-
horn with
control at
minimum
Look for
open
or
lowered value elec-
trolytic 6lter
block on
underside
of
chassis
directly
beneath
power
trans-
former.
To locate
defective unit
shunt
8 mike, high voltage
test
unit across
one
at a
time.
CROSLEY
f68.
Pronounced
hiss
in
background, on all stations, even
when
correctly tuned I Try
several
new
2A6's, 56's and 2A5's. If
this does
not
help
put
from 400,000
to
100,000
ohnrs
across the
prin.rary
of
the
first i.f.
trans-
former,
using the highest
pernrissible
value.
CROSLEY I68
No
reception
open :ection
oi
fll-
ter
conclenser
Nos. 23-24.
CROSLEY
170. Repeated
burning out
of 80
rectifier Cause is electrolytic
condenser,
part
29097, which shorts and
then
cleans itself.
Replace it.
l8
CROSLEY 170. Improving
tone
and volume
Connect a
2
to 4 mike
bypass across
the a.f. stage bias resistor.
Improving
sensitivity
Reduce value
of diode load
resistor
from .5
meg. to .35
or
.4
meg.
This will
also reduce back-
ground
noise.
CROSLEY
I70
Oscillation,
reception
onty when
finger
is
placed
on
grid
of
first
58
tube look
for
opening in
r.f.
oscil-
l:rtor
coil located
in
back
of band
srvitch.
cnosLEY t70,
t7t.
I-oss
of volume and noisy
operation
. . .
Examine
.0005
tubular condenser in
series with antenna
coil.
cRosLEY
t7l
Q.
A.
V. C. won't
work,
poor
volume
.
. . Bad section
in
candohm
resistor
part
number
W28471.
CROSLEY I73
Weak receptiolt
usually
can be
traced
to
open speaker 6eld.
Also
check 8 nrfd
25
volt electroll'tic
con-
nected
front first
a.f.78 suppressor
glid
to
tuning corrclenser.
CROSLEY
I78
No
control
of volurne
shorted
condenser
front
filament
of 32 tube.
CROSLEY
425
Distortion
check
dual
.5
mfd
condenser
which bypasses
the second
cletector
and
first a.f. bias
resistors
for leakage.
CROSLEY
5I'
Weak,
or intermittently
weak
Section
72
(.02,
2AO
v.,
6D6 cathode
bypass)
of
part
W2t36,23
dual tubular
condenser
is
probably
at fault regard-
less of
how
it may
test.
Snip
leads
and
substitute
a single
replacement
unit.
cRosLEY
5t5, 55t5,
FIVER
No reception
often
due to open
in
two-section Candohm resistor at
rear
of chassis
sub-base. Overall re-
sistance:
33,500 ohms; long
section,
25,000
ohms; short
section : 8,500 ohms.
In
event
of open in either
section,
and
original
replacement
not available,
use
S-watt resistor
of corresponding
ohm-
CROSLEY
5I7T
Distortion In
these sets
the
16
mfcl
6lter
is insulaterl
f ronr the chassis
by fiber
u'ashcrs. Since the
condcnser
is
in the rear
of
the
chassis
it is often
rused
for
li{ting the chassis. throu.ing
the
electroll'tic
can off center and short-
ing
to
chassis.
cRosLEY 515,
55t5,
FIVER
Dead
suspect
short
in 0.006
mfd.
condenser,
connected between
plate
2 and
ground
of 685. Unit is
in
sanre
tubular container with
0.02
mfd.
tone
control condenser. Center
term-
inal (going
to
plate
2 of.685) is com-
mon
to both sections;
therefore, to
eliminate
0.006 mfd.
section, clip
chassis
connection from
unit as close
as
possible
to
container
and install
single unit 0.006 mfd.
condenser
from
plate
of
685
to
chassis.
Intermittent
check for break
in voice
coil of speaker.
Defective
tuning mechanism
when
station
indicator
does not
follow
rotations
of
panel
control, trouble
often
due
to loose rivet
protruding
through rear
copper disc
on end of
control
shaft. By soldering rivet
to
disc,
trouble is
corrected.
Caution:
remove
celluloid disc from
between
copper
discs
before
soldering opera-
Jion.
CROSLEY 556
When the
volunre
colrtrol
fails in
this set, it often
is
difficult to
pr()curc
a
new
one
because of its special char-
acteristics. A
positive
substitute can
be made
with a 2000 or
3000 ohrn
wire-wound
potention-reter
and a 3pst
switch,
Connections
are
shorvr.r
ir.r
the
accompanying
schematic.
cnosLEY
60!
GEMIOX
Co,mmon faults,
in order
of
occur-
rence
in
the
6eld
Failure
of 0.5
condenser
under chassis,
power
trans-
former
lamination
hum. To cure such
hum lmsen
scveral
lockbolts,
hit lami-
nations
gcntly
with hammer
to set
them. When
hrrtn
stops
carefully
tighten
bolts, tapping
again
while
this
is
being done if
hum reappears. Noisy
volume
control.
Clean or replace.
Gentle
sanding with
0000
sandpapcr
and
rub
rvith
vascline
cleans
many
satisfac-
torily.
Freczing
of dial.
Replace drive
geer
or
rcpair by
smoothing burrs
on
geafand
holcs
where
it turns. Freezing
of rcgureration
contrbl.
Replacc.
Poor
tuning,
cuts off
ncar
l(X)
on dial. Check
tunirry
condcnscrs
for
spacing and
tracking.
Burrs
freqgently short
con-
denscrs when
over half meshed.