Technical information

O
RADIO
RETAILING'S
"Sqtcde
PHILCO TRANSITONE. When in-
stalling set
in 1934
Chevrolet do
not
mount
on right
side
near
coil if this
is
avoidable as it is
practically
impossible
to
remove motor noise due to chassis
pickup.
The battery lead
on
th€
model
10, cut to fasten
to the ammetcr
or
starter, is
the
guilty
wire.
Shielding
don t help, Lengthen
the lead,
shield
it and
thcn
run
it directly to
the bat-
tery,
connecting
the
lead
to the negative
and
the shield
to the
positive
post.
PHILCO
TRANSITONE
5, IO
No voltage, vibrator tubes and filter
check o.k.
replace
.01 nrfd. con-
denser connected between olatcs of
84 tube.
FORD
PHILCO
r935, r936
Intermittt.nt
check.01
nrftl con-
denser connected
to
volurue
cor-rtrol for
loose
connection.
PHILCO
T936 TRANSITONE.
Jntermittent
reception ,
Loose
an-
tenna
plug
insulator
should be filed to
almost
the level of
the
plug
as
it is too
long,
preventing
good
contact.
PHILCO
I937 MODELS
Distorted,
luzzy .
, . Check
the voice
coil
gap
for
steel filings. This is
quite
a
frequent
trouble.
Filings
get
behind
the heavy cardboard spacer
and
gradu-
ally
rvork
into
the
voice coil.
PIERCE.AIRO
PIERCE-AIRO
724.
Weak recep-
tion with oscillation.
Before making
any
adjustments look
for open cathode
by-pass condenser
in first and second
radio stages.
These are single unit.
Turn
chassis
upside down,
look on
radio-frequency coil
partitions,
Unit
is
one located nearest
rear
of
chassis, Use
0,5
mfd. replacements.
PILOT
93.
PILOT
When
this
a.c.-d.c.
superhet
seems
to
be out
of
'alignment,
whistles
all
over dial
.
.
.
Before
attempt-
ing to
realign check
by-pass
condensers
3x.l
in one
can
just
below
170-ohm
filament
resistor.
Heat
f rom
resistor
frequently
causes the
block
to leak or
open
and also
causes
fading.
Reptace
with
sebarate
tubular
condensers.
nLoT
293
Insensitive
poor
contact
in band
switch.
Clean
all
contacts
rvith
carbon
tetrachloride.
PILOT
DRAGON IO.
A.c. hum
level abnormally
high .
.
.
Look for
ground
at the
reflector
mounted
behind
the
pilot
light. Sharp
corner
oI
this
reflector frequently
pierces
the small
piece
of
fibre insulation
included
to
pre-
vent shorting of
filaments to
ground.
PILOT DRAGON
IO
Hum look
for
ground
at the
reflector mounted
behind the
pilot
light.
Replace fiber
insulation
at this
point.
46
RAC
6K2
Inoper:rtive on brtxtrlc:Lst
lrartrl otrly
.
invcstigation shora'erl
cvidencc
of
rnice . Layer of
tuoistttt'c
betweetr
broadcast
band,
nrica
trirtrrrcr
short-
ing
plates. Rentove trinrttrer, c!eatr
thoroughly antl
irrscrt ncw urica
separaters.
RAC
D-lr-2
Oscill:ttiorr
orr
lrigh frcqucncy
erttl of
short *:tvc
bitrrtl
Check oscill:rtor
qrir'l
resistor'.
This resistancc
is
n)(
)uht('(l
r )n
t{,p
o I
tlre turtirtg
con-
clcr
r
scr'.
RCA.VICTOR
RCA. Noisy or
erratic
reception in
rc-
cent
models using
a
745. mmf.d,. fixed
con-
denser
as oscillator coil
padder
. . . Re-
place
with condeuser
of same value
renroved fronr
oscillator
grid
lead and
replace
grid
condenser
with stock unit
having approxinrately same value. Pad-,
der
condenser
value
is
critical and stock
replacement will not
do
while
Srid
con-,
denser
value
is
not critical.
RCA
(GE).
Slipping dial on rubber
friction
type
dial
models
. . .
Slip
I
in.
bushing from an old knob
over shaft.
Solder
it
to
shaft
where
.rubber
gasket
originally
appeared.
Now
slip
AK 55
dial drive rubber
over bushing.
RCA,
GE.
Many
recent models
us-
ing Bradleyometer
variable
resistors.
If
these become
noisy remove the
covers,
with cloth, apply vaseline.
RCA
'MAGIC
EYE." Fluorescent
glow
crosses over
on strong stations, or
does not change
enough on any station
.
. . Change
value
of
resistor
connected
from ray
control electrode to
ground.
Make it larger if
the ray crosses,
smaller if it
doesn't
change enough.
RCA VICTOR HFz. HF4, UI30
Distortion
leaky .025 coupling
condenser from
6J5
phase
inverter
to
6F6.
Also check .1 condenser
be-
trveen 6J5 second audio and
other
6F6.
RCA
RO23
Weak . replace 8000
ohm
resistor
connected
between screen and
cathodc
of rf. and
if.
RCA RO-23
No
reception, set
surokes .
in-
spect
pilot
liglrt socket
for
loosc ternti-
nals which
cause leads
to sltort,
RCA
VICTOR R,T
Oscillation
open 8
mfd
(C-16)
in a can with
several
others. Replace
with
8
nrfd, 500 r'olt
trrrit.
RCA 58
Dcacl on
low frequency scttings of
rlial recluce
screen
voltages on
14.6 and 1A4 tubes
by replacing
25,000 screen
resistor with 50,000.
RCA
C6-l
Noisy,
even rvith
voluurc in off
posi-
tiotr Suspect 85
r-rhnr
section of
c:rndohnr resistor
unit.
RCA C&r2
Low Volume
.
. .
Check
volume con-
trol for
grounded
center arm.
RCA VTCTOR 6.K-2
Intermittent cutting off of
set and
dial
light
. . . small
rivet
in
center of
band
pilot
light shorting
to
ground.
RCA
T6.9
Crackling,
facling
.
voltage di-
vider
on
rear
underside
of ch:rssis nrak-
ing erratic contact rvith lug.
Replace
witl.r scparate resistors of 3500-13000-
d)-+tr-llJ otrnrs.
RCA
VICTOR
T6-9, C6-2,
T6-l
Hum with
the volume control
in
the eoctreme
minimum
position
.
.
.
if
6lter condensers
are
good,
reverse
either the
voice
coil
or the
hum-buck-
ine leads.
RCA R7
Low volume, oscillation
Check
14,300
ohm resistor bet,uveen the high
voltage
and
the
screen
grids.
This
resistor
often
gets
as
low as
5,000 ohms,
resulting
in high voltage
on the scre€n
grids.
This causes the 8000
ohm
re-
sistor
between screell ancl cathode to
heat
..ncl increase r.alue.
RCA-VICTOR
R7.
Crackling .
. .
Frequently
due to eyelet in
chassis
through
which
grid
lead
to 24 is brought
up. The
eyelet
is
not in any electrical
circuit, but when it works loose the ca-
pacity
of the
grid
lead
passing
through
it
varies
with
respect
to
ground.
Renrove
or
solder the eyelet.
RCA
R7.
(WEST.
WRlo,
cE
s22)
Rubber
friction
roller
of dial
wears out
.
. Remove
tuning
dial
by
loosening
its
two setscrews
and remove roller
from
shaft.
Cut off
a
piece
of
rubber
tape,
not
friction
tape,
8l inches
long and
I
inch
wide and
wrap it tightly
around
the
shaft, in
the
position
of
the
old
roller,
layer
over layer.
The tape will
form
a
new
roller.
RCA R7
(WESTTNGHOUSE
WRlo,
GE S.22>. Slipping dial
.
. Groove
wears
in rubber friction
roller but not
exactly in middle, Remove
dial,
loosen
screws holding
shaft to
chassis,
remove
roller
from
shaft and reverse.
Replace
dial
while
holding
shaft
and
roller
firmly
down
against dial and
tightening shaft
holding screws.
(I.F.
175 kc.)