Technical information

O
RADIO
RETAITING'S
,,,
e/f/ui@
MOTOROLA
77A.
'Loud
whistle
and
distor.ted
reception
in
early
nrotlels
. .
Generally
caused
by
breaking
of
solid
wire cottnectiotr
betweetr
tone
con-
trol
and
small
fixed
condenser
mounted
on
chassis
directly
behind
control.
The
wire is
covered
with
cotton
braid
and
frequently
appears
to be
ok'
Continuity
test
shovvs
up
def ect.
Replace
with
flexible
wire, such
as
is. used
in
later
nrodels.
Dead
set .
Suspect
the
vi-
brator
first.
Renrove
from
housing
and
check
the
two
.007
condeuser
shutrted
across
the
rectif-ving
vibrator
points.
Jhey
f
requently
short.
Replace
witlt
i600
volt, .007,
oil-filled
units.
Static
when car
is in
motiort
Sorlletintes
caused
by brokerl
soldered
joint
between
antenna
coil shield
and
chassts. Or
by
corrosion
of
spring contact
grounding
the variables.
Bond
rotors
to chassis
for
permaneut
repair.
MOTOROLA
78
Poor tone check
the
voice coil
and field
to
see
if these connections
have
been
reversed.
This causes the
voice
coil to become
charred.
If
such
is the
case replace
cone and voice
coil.
MOTOROLA
80
Dead,
draws high
current
re-
place
.008
mfd.
buffer condenser
from
plate
of
0Zl
to
ground.
MOTOROLA
82A,
IO9KI
Violent
oscillation
or thunrping
on
high
frequency
end
of s.w.
bancl, ;rround
20 nrc. .
. .
insert 60
ohm
non-inductive
resistor
directly
in the
grirl
lead at
the
grid
cap
of
the
mixer tube.
MOTOROLA
89KI
Inrpropt'r
pushbuttorr
tuning
adjust
relay reversing
contacts
so that
action
is
positive.
MOTOROLA
seKr
(CLOCK
TUNINGI
Failure to turn
on
.
.
relaY
spring
too
stiff.
Turns
on, but
inter-
mittently
fails
to
tune
when
buttons
are
pushed,
relay contacts
dirty
or
contact springs
not
stiff
enough.
MOTOROLA I24
Tuning
nrotor
runs constantly
white wire
grounrlcd
rvhere
it
goes
throrrgh
dial assembly.
MOTOROLA
3.+5
When
installing
this set
in a
1939
Pl-v-nrouth
using
a
hinge antenna
it
ofien
is necessary
to
shield
the
lead-in
right
up
to the
hinge
and
bond
shield
to
door
trinr
to
completely
eliminate
nrotor
noise.
MOTOROLA
860, 880
Quive
11.
cffect
rvhen
tlriving
ovcr
rough
roacls. \Ia1' be acconrpanied
b1
sharp
loss of
volrrnre
and
tone .
lrut-
ing
sn-itch
has insufficient clearance
be-
trveen
its contact
points. lloving
contacl
vibrates, touching fixed contract.
Ben<
38
rlolvn
part
of
the
bracket
holding
spring
of
moving
contact
until
gap is
grea'l
enough
rvithout
hindering
closing
action
MOTOROLA
1935.
Installation in
29, 30 and 3l Chevrolets
. . . Bond all
metal in
overhead
frame
of
car, such as
the windshield adjustment
and corner
braces.
Run antenna
lead in shield to
within 6 inches of
antenna.' Bond
an-
tenna
lead
to
dash and dash to
bulk-
head. Run bond
from firewall up right
front
post
to border on
top members.
Place
grounded
screen on
floor
boards
and bond
motor
and
all choke
and
throttle
rods
running
from motor to
driver's compartment.
If
care is taken
no
suppressors
are needed.
MQTOROLA
GOLDEN
VOTCE t936
llulllcrl
tone,
distortiou
at
ltru lei'el
. opcrl
r-olunre
colltl'()ls, rtpllrcc
n'ith
.;t)0.(n0 ohur noterrtiotrreter.
MOTOROLA
I938
MODELS
Set
blurbles
when
jarred
check
i.f.
transformer
and
tube
shields
for
good
ground
to
chassis.
A
good
cure is
to
solder
the
shields
to
the
chassis.
MOTOROLA
DELUXE
Noisv, loss
of volunte
look
for
shortecl leads in
shieldeil cable
'fronr
r.f. section in
tuning
head
to
auclio
section in
speaker housing.
MOTO.MASTER
DELUX
No reception
Check
.008
mfd
2000
volt
condensers
from
one
recti-
fier
plate.
oLDSMOBTLE
405046, PONTTAC
54,+268
Mushy
tone,
fading
replace .02
ntfd (C21A)
condenser
coupling
triode
plate
of 6I;7 to
control
grid
of 85.
Also
.0.{
mfd (C218)
betweerr triode
srirl rn,l ,'onler rnn nI
r'ulttrrtc control.
b''Y
*"_
oRtoLE
400
No
plate
or
screen
voltages
oPer
750
ohm
filtcr choke.
Bridgc
choke rvitl
sinrilar
l0
rvatt
resistor.
No
noticeablt
increase
in hunr.
PAC|FtC
34
Weak
on broadcast. O.K. on S.W.
nnen nrimr rr. nf
brnlrlcast
antenna
... vyLrr
coirpling coil.
PHILCO
PHILCO.
When shot friction drrve
allows dial to
slide
oft new allwave
models...Make
a
small
dog-ear orr
each end of track engaged by driver and
it won't run
oft
the
track again.
PHILCO.
When
"Shadowgraph"
tuning
indicators fail
to
indicate
check
up on the antenna. If it is too short, or
so
inefficient that it does not
pick
up
strong
signals this will
happen.
PHILCO.
Where
dbl
cables
show
a
tendency
to slip
at several
points
smear
thc
cable
with
rosin.
PHILCO'
High
ond
loza
freqwncY
trimnters
car
be
dirtsted
zaitho*
an
otrt-
but
mctel
oft
sets equiqqeil
uith
Shadoztt-
'graph
tuning
indicators
by
frst
tutting
a
station
operating
on
7,400
kc. and
adjusting
for
narrozo
shadott
dnd then
repeating
thc
'\roccss
on a
lotu-frequency
signal.
PHILCO
T-2
Motorboats
while
heating
then dead
, .
check for short
between
windings
of second
i.f, transformer
by
measuring
the 75
diode
plates
to
ground. Should
be
zero with aerial
disconnected,
nega-
tive
with signal.
If
otherwise,
remove
coil and
tape
coil leads
to
Prevent
shorting.
PHILCO CT2
Sizzling
rvhistle
rotor
u'iper ir
first r.f.
section
of tuning
condenser
not
making
good
contact.
Clean
and bend
spring to
insure
good
contact.
PHTLCO
45
fntermittent
for
open or
short.
check
wave
trap
PHILCO 5.
Frying
or crackling
in
early serial
numbers.
If not
in
elimi-
nator remove
grid
clip
from 6.{7
caP
and
remove lead from
clip.
IJsing
same
size
stranded
wire
with
good
insulation
wind r.f. choke of
five
turns on
clip, re-
connect lead.
For
obstinate
cases wind
thirty turns
number 16 solid,
cc wire
around
pencil.
Withdraw
pencil
and
place
choke
so formed in
A lead between
low voltage
r.f. choke
and
heater ter-
minal of 84.
Keep choke
in the
vibrator
section of
base. Solder
and
tape splices.
Late serial
numbers have
these
chokes.
PHILCO 5. Oscillations and
code sig-
nal interference
between 500 and 750 kc.
in Transitone model . . . Usually
due
to
defective
condenser connected between
plate
of
output 4l
and
ground,
Located
directty beneath socket.
Replace
with
.006.
PHILCO
5.
No volumc,
eliminator
output
only
95 volts.
Push
down
on
upper
vibrator
contact
so
that
spacing
is
equal
between
armature
and
both
con-
tacti.
Erratic
vibrator
iction.
Make
sure
resistor across
contacts
is 50
ohms.
Buzz,
tor
which
vibrator
is
not
respon-
sible.
Replace 2A7.
PHILCO
5, 7.
Scratching
noise
when
tuning
Tighten volume
control
nut
in
chaisis
and
be
sure
it is well
groundcd.
PHILCO FT6
ltnul lrtv.z
tvlren sct
is turnert
ott. tlis-
;Ll)l)cafs
ulrcn
cathoclcs of 75
or'
-12
lrre
grouttrlc<l
replacc
dotrblc
l0
rr[rl.
cathi,rrlc
bypass.
'l'his
condenscr
is
irr
tlrc tubc courpiLrtnrent oi tlre
rcccivcr'.
PHILCO
10.
Audio
howl
over
entirc
dial,
. .
GcnerallY
causcd
bY
loose
shield
ovcr
i.f.
tube
39
ot
14-