Technical information

.O
RADIO
RETAITING'5
,,,
atui@
MAJESTIC
66.
Normal
voltages,
vi-
brator
ok but
s€t don't
play
. . ' Try
re-
moving shield
of
i.f. coil,
placing
insu-
lating
paper
around
coil
framc.
MAJESTIC
66.
Intermittent
oPera-
tion
when
car
is operated
over
rough
roads . .
Look
for broken
shielded
ground
wire
leading
inside
o,f
plug
at
iear of
set.
Take
oft
plug
and
unscrery,
soldering
wire.
MAJESTIC 66.
No screen
voltages.
Check
10,000 ohm
resistor
just
below
6E7 and, 6C7
and
if
burned
out
replace
with
one
having higher wattage
rating.
Plate and screen
voltages below
normal.
Check
center tapped
filter choke
(under-
neath set about and
inch away
from the
A battery
female cabte
connector).
If
grounded
side
is
open
or
partially
open
there is no
grid
return to
ground
for
the output
tube and lack of
bias boosts
plate
current
to.
point
where
dfoP
through choke
becomes
abnormally
great.
MAJESTIC 66. Installaticn
hints
. . . To
greatly
reduce
motor
noise
pick-
up conducted
to chassis
by
pilot
light
lead,
make it easier to
remove the
set,
permit
the use of
the set
without the
pilot
light burning
in
daylight
proceed
as
follows: Before
nraking the
installa-
tion renrove
the remote
control
pilot
light
feed
rvire
from the
chassis
by un-
soldering
it
inside or cutting
it off
just
outside the
case. When
the remote
con-
trol unit has beeu
mounted
connect the
pilot
lamp wire to the
tail
lamp
post
on
the
lighting switch
hy holding wire
to
each
post
and snappiiig
switch through
its various
positior-rs.
MAJESTIC
66.
No reception,
volt-
ages
ok. .
Look
for open
grid
return
condensers
across
the 300,000
ohm
a.v.c.
resistors
(marked
Cl
and C2
on manu-
facturer's
diagram).
These
are the small
tubular
type
of
.0J
mfd. condensers
found hanging across the
first two
r,f.
coils. They
opcn, due
to vibration.
Ex-
cessive
current drain,
vibrator
works
cr-
ratically,
. . Change
"Globar"
resistor
across
vibrator
transformer
secondary.
Testing
B voltage .
Bottom cover
need not
be
removed.
Simply
put
plus
end of meter
to
the
i,f.
trimmer
cou-
denscr terminal on top of set. Reception
ok
with cover oft, distorted with
cover,
especially on low volume . . .
Tap metal
spider
of speaker
lightly downward,
re-
centering cone. New
sets
sometimes
come through bad as they
are tested
at the
factory
with the
cover oft and
then
packed.
Set
alive
from
grid
of
6C7
only,
dead
from
preceding
tubes
.
. .
Look for open second i.f.
trans-
former
secondary. Squeals and
oscilla-
tion on lower wavelengths,
from about
1,100 kc.
up
. . Change 6A7.
Thc
tube
defect
will
not
show up
in
e
checker.
MAJESTIC 66 AUTO RADIO
One side of
rectifier tube not work-
ing
adjust
the vibrator carefuily
according to original directions so
that
both
plates
handle equal
load.
30
UAJESTIC
70.
Dial
cable
rePlace'
ments
arc easily
made
if
the
ProPer
template
is used. Cut
a
36 in.
length'
4 in. wide
from
I
to
I in. thick
board.
Drive
a wire
nail almost
home
in thc
exact
center of
the
broad side end
one
near
each
end,
l5l in.
from the center.
Lay
a length
of suitable
cablc
material
alongside
the
nails and
form and solder
two
iingle
and one
double
loops
around
the
nails to
match
the
anchor
pins
on
cable
sheaves.
MAJITSTIC
70.
Fading
Don't
trust
plier-tightened knurled
nuts
on
powerpack terminal
strip.
Rcmove
top
strip
and tighten
all
hexagonal
nuts
on
the bottom
mounting.
If
these
are
loose
screw heads
underneath
will
not
make
contact
with lugs.
Open
a.f.
26 bias
re-
sistor
remove
knob
from
hum con-
trol
at rear
of chassis.
Remove
nut
holding
hum
control
and
insulating
bushing.
Replace
.without
insulating
bushing
and set
will
play
with
good
volume but
bad
hum. Sell
customer
re-
placement
control
job.
Intermittent
buzzing
. Generally
a
cathode
to
heater short
in 27
tube,
when
heated.
MAJESTIC
70.
Holding dial shaft
from
turning while
replacing
cable . .
.
Fasten one end of the
new cablc to
its
spindle and wind
it until the dial
is tight
against its stop. To hold
it
therc,
while
the other end of the cable is being
ad-
justed,
clamp a
small Stiltson
wrench
to the tuning shaft on the outside
of
the chassis and brace the wrench handle
against the
volume
control shaft.
MAJESTIC
708.
No
grid
reading
on
7l's
Check
pilot
light socket,
It
frequently
shorts to
grouud.
MAJESTIC
70, 7r
Weak, intermittent
. .Look
for
a
fungus
growth
or
mould on
fabpic in-
sulation
of R.F.
rviring,
no
rubber under
fabric
of
wire.
Rewire with rubber
and
varnished
cambric insulated wire.
MAJESTIC
7r,
72
Dead
.
.
.
look for open
windings
in
audio
transformers in
these early
elec-
tric
receivers.
IUAJESTIC 70,
90.
Frying
noise,'
sounds
like noisy
audio
transformer
but
is
not
. . . Often
due to
corroded
and
loose
lcads in
the
baltast
unit.
Take
cover oft,
loosen
resistance
wire
leads,
ctcan
them well
and
replace,
tightening
contacts
well.
MAJESTIC
70. 90
Neutralizing
tool on
hand too large
in
diameter
to
go
through
condenser adjust-
ment
holes
at
top
of chasis
.
. .
Remove
hex
bolts
from neutralizing condensers
and
saw
slits so
that they may be turned
with an
insulated
screwdriver.
MAJESTIC 90.
Set
plays
for about
an
hour then
fades in volume, though
stations
are still
heard weakly
Look
for
partially
shorted r.f.
5 mike
condenser
located at
front
of chassis
with
chassis upside down,
on left side.
MAfFTrc 90
Antenna
choke
tuned
by
a
.001 con-
denser
frequently
opens uP . .
.
Can
be
replaced
with
the
good
coil
section
of
a
175
kc., i.f.
transformer
from an
old
Radiola
80.
Saw
through
the
center
of woodesr
sPool
and
mount
good
coil
in
chassis.
A
hole
is
already
fhere.
MAJESTIC
90. Common
troubles
are
the
shorting
of the
detector
filter
condenser
or
opening
of
the 2,000
ohm
filter choke.
A
2,000 ohm
resistor
can
be
substituted
for
the choke.
MAIEST|C
90
Loud,
irritating buzz
occurring
at
short
intervals
Frequently
caused
by
poor
connection
where
resistance
wirq
of ballast
unit
is attached
to
the
prong.
Clean
and
tighten.
MAJESTIC
90.
"Burping"
on dance
volume
..
. Usually
due
to
poorly
matched
45's.
Speaker
rattle
Smear
thc overlap
of the cone
with collodion.
Sometimes
it
is
necessary to
remove
the
wires which normally
hold the
over-
lap in
place.
MAJESTIC 90. Carrier
hum.
Removc
receptacle
plate
on
floor outlet
from
which set
gets powet
and
fasten
ground
lead to
Gem
B box
by means of mount-
ing
screw.
Such a
ground
is a
positive
remedy where
iron conduit is
well
grounded.
MAJESTIC
90.
Viotent oscillation,
especially
on high
frequencies, when
vol-
ume is
turned
up on
station . . .
Shunt a
I
to
I
mike
condcrrser
across
each of the
r.f.
bypasses
tocated
bcneath
the chassis.
These
are large,
inclosed
in
tin.
MAJESTIC 90
Lacks
pep. .
.
.
Check
cable
and con-
nections
between
power pack
and
chassis. Often
sections
of
this
cable
are
open.
MAJESTIC
90. Intermittent reception
. ,
. If complete set of new tubes does
not cure this
replace 2.5 mfd. condenser
located on inside of
chassis
wall.
These
open
intermittently.
MAJESTIC
90.
No
ptate
voltage
.
'
Generally
due to
shortid
filter condenser
(2
mfd)
in
pack,
connccted
from black
lead to
green
lead through
2,@0 ohm
choke to
red lead. Breakdown
usually
rrrins choke.
Replace both.
MAJESTIC 90. rOO
Cuts off to
half
volume, stlucals at
full volume intermittently
.
replace
both
.5
mfd
condenser bypassing cath-
ode bias.
MAJESTIC
9OB
Hunr, fading
.
. .
. lift
rubber cor'-
cled
wires of cable
so
as to clear
116
ohrn
uon irrductive
centertap
t'eslstot'.
I
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