Technical information

O
RADIO
RETAITING'S
"Sauie
RADIOLA
{.t, 46
Difficulty
in
aligning
Probably
due to
shorted
turns
on the small,
uni-
versal-wound
plate
coil.
Replace
this
coil.
RADIOLA
44, 46.
Set
plays
on
one or
two stations
but it seems
impossiblb to
align
tuning condenser .
Replace
the
first,
unshielded, r.f.
coil,
which is fre-
quently
affected by moisture
and cli-
matic conditions.
RCA 44,
46. To
tune in
poiice
calls
. Trlmmers
may
be adjusted to
pick
ap
l7l2
kc. stations
and still
get
95
per
cent of
the broadcast
band. Trimmers
are hidden
at
front
of
set chassis
and it
is necessary
to remove
the chassis
from
the cabinet
to adjust
them.
Right hand
trimmer,
on the detector,
has
a habit
of shorting. Install
slightly
thicker
piece
of
mica
and re-align.
RCA 44, +6. Loss
of volume, se-
lectivity,
sensitivity after
several
years
of
use.
If
voltages
and tubes check ok
trouble
is u5ually
caused by
wear in the
gang
condenser,
permitting
the rotor
sections
to shift.
Re-align
these by
means
of the adjusting
screws
at each
end
of
the stator
sections.
Select a sta-
tion
between 600
and 650
kc.
and
adiust
for maximum
volume.
Then
adjust
the
trimmers
at
the 1,500
kc. end
and re-
peat
both
operations
once
again.
A
235
in
the 2nd r.f.
stage
will improve
tonc
on local
stations
and
low
volume
settings.
RADIOLA 44,46 AC. Low, or
no
plate
voltage.
Often due
to
grounded
coup-
ling reactor
in detector
plate
circuit.
This is in
small,
brown housing beneath
tuning unit and
is insulated by
thin
pitch
coating.
Slip
insulation between,
chcke and
chassis.
RADIOLA
11,
+6, 17. Squeals
and
howls
. . Check contact made
bv little
wiping
clips fastened
to bottom
oi stage
shields and
see if they have
sprung or
are dirty.
VICTOR
RE 45
PHONO
Low
Volunre
adjust
pickup
nlagnets
as close
as
possible
by
squeez-
irrg
n'ith pliers..\djust
arrrrature.
Ii
rubbers
have
harclened,
r.eplace.
VICTOR
RE,ts, 52,
75.
Chassis
shorts.
Often
caused
by
steel needles
falling
down from
phonograph
compart-
ment
and
shorting socket
lugs
to
ground.
RCA
-46.
Oscillation
experienced,
identified
as
too
small
an
antinna
load
, .
. Make
sure
all
shields
and
grounds
are
ok,
then
connect
a .001
or .005
con_
denser
from
antenna
to
ground
and re-
align
antenna
stage.
Tiglten
up
entire
cond€nser-
Slng
white
set is
open
as
snrttlng
ot
elther
rotor
or stator plates
is
quite
common.
RCA-V|CTOR
{7.
Fades
on locals,
volume
can
be
brought
back
by
snapping
a.c. switch
on and
off . .
. Plate
supply
of
first and
second
r.f.
tubes feeds
through
phono-
record
switch
and
poor
contact here
is
usual
cause
of
grief.
50
RCA 48.
Cutting in and
out
of
recep-
tion
is
sometimes
caused
by
slufing off of
the
plating
on
tuning
condensers. Hum,
noticeable
only
whan
recordr
8rc
played,
is cured
by
a 5,000
ohm
resistor
shunted
across
the secondary
of
the
pickup
input
transformer.
RADIOLA
.I8
Intermittant
examine
plates
of
variable
condenser
for
filings.
The
plates
of
this
condenser
are
made
of a
magnetic
material
and
should
be kept
clear of
6lings. Blow
out
thoroughly
*'ith
air
pressure.
RCA
48
Dead
or
intermittent
. . .
Check
tht
detector
plate
choke under
the oblonf
shield
at right
of tuning
condensci
Also,
the r.f.
choke under
the
shield
a
left
of tuning
condenser.
RCA
50, 55, 59. Poor
volume, no
dx.
Remove
a.v.c. 27.
If volume
immediatety
improves
disconnect
,l mfd. condenser
in
power
pack
fastened
to onc cnd of I
meg.
resistor and
usually
wired with
blue lead,
Connect new condenser
from
this
point
to
ground.
For
temporary re-
pair
simply
omit
condenser.
RADtOll
50,
t0
Distortion
replace
110,000
ohnr
resistor
from
B
plus
to
cathode of
second
detector.
This
resistor
decreases
in
value
and
supplies
excess
bias volt-
age
to this
tube.
RCA.VICTOR
R5O, R55.
RAE59
Distortion
and lack
of
volume
. .
Check
primary
of
interstage
trans-
former.
The winding
with
the
yellow
lead
.opens
up. Disconnect
the
yellow
lead
from the number
5 terminal
bn the
8-terminal
strip of
powerpack.
Con-
tinuity
test will
probably
show open
or
high resistance.
RCA
R50, GE H32,
R55,
RAE59.
Sets
play
only when 27
a,v,c. tube is
re-
moved
.
. . Look for
open resistor
in
a.v..c.
return, also for
high negative bias
on r.f. and i.f. control
grids.
Oscillation
. . . Usually caused by open
circuit in
.l
mike screen
by-pass condenser. Fad-
ing . . .,Look for open or
leaky .l by-
pass
across resistor in
a.v.c. circuit,
usually
found
in the
power pack
con-
nected to
the bluc lead
from
the
con-
denser
block.
RCA
55.
No reception
except
powerful
locals,
voltages,
tubes ok
. . .
Check,
prefcrably
by
substitution,
.1
mike
condenser
connected
between
blue
and
black
leads,
located
in
capacitor
pack
mounted
on
separate
power
unit.
Cut loose
blue lead
at resistor
mounting
board
and
substitute
600 volt
tubular
replacement
from
vacated
terminal
to
ground.
Trouble
is
generally
high
re-
sistance
leak
of
the
order
of l/10
meg-
ohm,
which
upsets
a.v.c.
circuit.
(IF
175
kc.)
RCA R55
Fading
. .
.
check the .0024 mfd
con-
denser
across the
plate
and cathode
of
the a.v.c.
tube for open
or
leak.
VICTOR
RE57.
Set dead . ...' Re-
move
panel
mounting
rivets
carefully,
turn
panel
over and
check value
of 2
watt resistor
in
detector
circuit.
It
should
be I
or ll megohms.
RCA RAE59.
Flat
tone
quality
when used close to
high-powered local
stations . Trouble is in a.v.c. action.
Over
'control
is
exerted.
Look for
500,-
000 ohm
resistor from
plate
of a.v.c.
tube
to
ground.
Open the
ground
end
and
insert
a 300.000 ohm
resistor
in
series, replacing
the
ground
connection.
Now release
the
r.f. and i.f. leads from
the
plate
of the a.v.c. tube and
placc
them at the
junction
of the two re-
sistors, by-passing this
junction
to
groun.d
with
a
i
mfd.
condenser.
RCA 60
Fit<ling,
distoltiorr
opell
secon<l-
irr-\
rri
tttttli,t
ctittplinX
tliillsi{)l.ltref.
RCA
60. Noisy reception
Look
for
bad r.f.
plate
choke in
r.f. trans-
former
assembty.
RCA
60. Low
volume
or
no signals
and
low
plate
voltage
.
. .
Measure
resist-
ance
of
black carbon
20,000
ohm
bleeder
resistor
in
pack.
Usually
has decreased
in
value. Replace
with 3
or 5 watt
unit.
RADIOLA
60
Weak
usually 20,000
ohm
bleeder resistor,
connected
between
plate
supply
and
cathodes
of
27s in
r.f.
and i.f.
stages, is at fault
due to
large
decrease in
resistance.
-\fter
replac-
ing
this component,
however,
volume
is
often not
up to expectations,
and
voltages
ancl
continuity
tests
will fail
to disclose
additional
defects.
This
receiver
has
no
first audio
stage,
uses
a.
27
in
gridleak
detection
coupled
to
a 71A output
tube.
RCA
60, 62.
Low
volunre.
Check
for
decline
in value
of
the 20.000-ohrn
bleeder
resistor
located
beneath
the
pack.
RADIOLA
@,62,6,
17, lE,
33. Rear
bearing
for.
gang
condenser
shaft is
simply
hole
drilled in
plate.
Wear
per-
mits
wobble
and resulting
frequency
change
sounds like
motor-boatin&
es-
pecially
at high-frequcncy
end. Secure
piece
of
brass 3,/64
in.
thick,
I
in.
wide
and
3l in. long.
Bend it
at right
angles
I
in. from
one
end. Holding
thc biass
horizontally,
the
short
"leg"
down, in-
sert
it
from
side
to side under
the shaft
between
the second
and third condenscr,
jamming
it
firmly
between
shaft and
base.
RADIOLA
62
Dead,
low
plate
voltage, high
biar
rn
all tubes
. . . suspect mica con
denser
connected f ror-r'r
plate
of
sec-
ond
detector
to
grouncl.