Technical information

O
RADIO
RETAILING'S
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RCA T7.5
Distortion,
high
plate
current
in 6F6
output stage
Increase
bias resistor
to its normal
value
and distortion
rvill
clisappear.
RCA 7U2
Ddtd,
no
plirtc
voltage.
.
. .
Usually
caused
by
C32,
a .25 nrfd condenser
bypassing
high voliage
filters. Re-
placb
with
600
volt
unit.
RCA VICTOR_88T6,
Noisy, intermittent
. air
dielectric
trimnrers
shorted
intermittentlv
bv
met:rllic
fuzz.
Flash
with high
voltag;'
to burn
off
fuzz.
Conderrser across
scc-
or-rdary of
antenna
coil
nray
be
flashcd
without
disconnecting
if wave l;and
switch
is tulne<l
to
right
settirrg.
RCA
R8
Oscillation
check
.1
mfd
con-
denser (C14)
bypassing
plate
of
27
oscillator.
RCA VICTOR
R8
Rubber
ring
on dial
drive assembly
slips
on shaft
. make thin
metal
washer
the
size of
the rubber
ring. Slip
washer
over
shaft
and hold in
place
by
a small
pin
through
shait and solclered
to
washer. Then pin
ring
to rvasher.
RCA
T-8-l,t
Oscillation. .
. . Grid leak on rear top
of
main
tuning
condenser
has
changed
its. resistance. Replace s'ith
identical
unlt.
RCA D9-r9
Weak,
trming eye will not function,
seconcl i.f. trimmer
will not
peak
.
This
is a
radio-phono
combination,
ex-
amination
of
the second i.f. transformer
disclosed
the trimmers
soaked in
oil that
had
dripped from
the
phono
motor.
Clean
trintmers
thoroughly
and
realign.
Use
oil sparingly
on
the nrotor.
RCA 9K
Set dead, no
screen
voltage
Check candohm
resistor
mounted
under
re.al
of
chassis.
R'esistance
should be 22,000
ohms.
RCA
VICTOR
9K
This
receiver
has
a
five
band
dial
but only
four positions
of the
band
switch. A
stop is
provided
to eliminate
the dead
position.
This
should always
be in
place
when
the
set
leaves
the
shop
otherrvise
a complaint
of one dead
band
might
be received.
RCA
VICTOR
9K. 9KI
Dead
at
550 kc
end of dial
.
re-
place
the small
condenser
on
top
of
condenser
gang
and
connected to
grid
of 6JZ
oscillator
with a
.0001 mmf
mica.
RCA
9KI
L-utoff
on str(xrg
signals
Check
nrica condenscr
coupling
r.f.
st:lge to 6rst
detector-.
RCA 9KI
Intermittant,
tuning
eye ope rative
even though
set cuts off
.
replace
.01
mfd.
audio
coupling
condenser
be-
tween
6F5
plate
and
6F6
grid.
RCA 9K2
Noise in
audio amplifier
reheat
all
connections
on
6F5 socket,
especially
cathode
to
ground
junction.
RCA 9K2
Interntittent
operation,
operation
re-
stored
if set
is
jarred
replace
audio
coupling
condenser
between
6F5
and 6L6
with
.l
mfd
600
volt.
RCA VICTOR
9K3
Insufficient
bass
shunt
a 25
nfd., 25 volt bypass
across the
6L6
cathode
resistor.
RCA
9K3
Chokes
up
on strong
signals
look for
high resistance
leak
between
catJrode to
filament
of
6H6.
RCA
9T,
9K2
Poor
reception
on broadcast
band,
O.K.
on
short waves
. . . replace
screen
resistor
on
6L7.
R.C.A.
9SX
Hunr
ofl
new
sets,
also
buzzing
noise
connect
additional
2
mfi.
200
volt
6lter
across
rectifier
plate
to
chassis.
RCA
9U
Distortion.
Check
Z0
mfd
cathode
bypass
on
6L6
output
tube,
for
leakage
or short.
RCA
RIO
Noise
similar
to loose
tube
elentents
.
nray
be
caused by
loose metal
grommet
rattling
on chassis.
The
control
grid
lead
of the first
detector
passes
through this
opening
and
un-
doubtedly
picks
up
the small induced
voltage
thus
generated
and
anrplifies
it
greatly.
RCA
R.I I
Fading
after
few
minutes operation
.
. .
Replace
'27
in A.Y.C.
socket
rvith
Sparton
485.
RCA-V|CTOR
Cr r-l
Set changes
volume badly
rvhen
speech-music control
is vari6d . . . In-
stall
new capacitor
pack.
This
pack
is
on.the
front of the
chassis and connects
to both volume
and
speech-music con-
trols.
RCA Ril-eE 62
Intermittent.
.
. replace
C
l8 a.l mfd.
condenser
in A.V.C.
network. This
condenser
located in
capacity
pack
end
can
be distinguished
by
whitc
lead
that
goes
through
resistor
board,
RCA RI I
Distor'tion
on
powerful
locals,
a.v.c.
doesn't
generate
sufficient voltage to
keep
r.f.
from
ovbrloading detector
.
.
connect 2 meg. resistor
between
junctions
of
RlO
and
Rll
and
Rl6
and Rl7
RCA fl. Set stops
playing
at rrr-
tervals after
27 a.v.c. tube
has
been
re-
placed
. Use an
old
type,
straight-
sidr'
27 in this
position.
Excessive
heating
is
probably
at the root of the
trouble.
RCA-VICTOR Clr,
C13.
I
nter-
mittent reception,
volume
periodically
rising sharply to nearly full output and
then
dropping
back to normal . .
.
This
is
"cut
in" rather
than
"cut
out" trouble
and to
cure it replace audio
coupling
unit
at the
front
right of dial, looking
at the
top of chassis. Tone compensation con-
densers open up. Be
sure to
get
the
im-
proved
unit for replacement as an
orig-
inal
would
probably
have the same
trouble eventually. Do
not cut the
leads
as new leads come with
replacement.
Unsolder
old leads at volume control
and
tone switch arms.
RCA Rlz.
Motorboating..
.
Re-
place
type 47
tubes and connect
a 5,000
ohm
resistor
in
series
with the
screens
to
prevcnt
recurrence
of
the trouble,
ncA
ct3-2
Excessive
hum
level . .
. open 8 mfd.
a.f.
plate
bypass.
Replace with
8 mfd.
250
volt
unit, clipping red
lead on
capacitor.
RCA
I3K
Fades
after several hours of
ooera-
tion clreck
C85
and
C86,
10 mfd
filter condensers
which.
are seDarate
units connected in
parallel.
When one
of these open, set fades.
RCA
IsK
Intermittent
broken or
shorted
voice
coil.
Replace
with
new
cilne.
RCA VICTOR
IsK
Magic
eye inoperative,
lights
up
but
does
not
close
.
.
movable
arm of
tuning
tube
control
shorting
to metal
cover.
Due
to the
design of
this con-
trol
the
clearance
at
this
point
is very.
small when
the arm is
put
under
ten-
sion. Take
control
apart
and bend arm
so
it
clears
RCA
RADIOLA I7
Oscillation
over
upper half
of
dial
.
Change 1000
ohm
grid
resistor
in
second r.f.
stage
to 2000
ohms.
47