Technical information
@
RADIO
RETAITING'S
",
qZuie
MAJESTIC
3OO
Overload
with
volume
all
on,
still
not
enough
volume
.
.
. high
resistance
leak
in
coupling
condenser
connecting
to
tube
side
of volume
control.
MAJESTTC
3OO
Motorboating
u'hen
volume
is
atl-
vanced
. replace l0
rufd
electrolytic.
C3
in
schematic
MAJESTIC
300
SERIES.
Weak
sig-
nals,
heard
only
at
critical
point
of
volume
control
Condensir
can
marked
C and D
houses
two capacitors,
C17
a .l
mfd.
and
C24.
a .25
mfd.
A
leak
of
one
or
mcjre
megs
from
Cl7 to
grotrnd
or
to
C24 causes
trouble.
Ordinary
ohmmeters
will
not
detect
it.
Cut both
leads
coming
out from
holes
in
can
marked
C and D
and
connect
a
good
.l
mfd.
unit
externatly
in its
place.
For
solution
of other
troubles
in
this
series
check
each
I
watt
carbon
resistor
for
more
than
25
per
cent
change
in
value.
(I.F.
175
kc.)
MAJESTIC
310A.
Lack
of sensi-
tivity
Try
placing
20,000
or 30.000
ohm
resistor
across
grid
return
of i.f.
transformer
to
ground.
Cutting in and
out
Look
for
high
resistance
con-
nection
between poorly
cleaned
en-
ameled
voice-coil
wire
and leads.
MAJESTTC
3
t0-8
On
all sets
of ihi.
typ"
using
i.f.
plate
feed for
automatic
volunrb
con-
trol,
a slight
leak will
bias
the control
grids
positive,
causing
them
to block.
Replace
defective
condenser
with
50
to 100 nmf.
mica
condenser.
MAJESTIC
370.
No local
reception
rvith
grid
cap
off i.f.
tube
. .
Cauie is
generally
shorted
i.f.
ioil.
Remove
it
fronr
case.
bend
back
the lug
and
put
a
piece
of fishpaper
between
coil
and
casc.
MAJESTIC
380
Low
volunre,
hum
check
G57
AS
and
G58AS tubes. These
tubes
cannot be replaced with
G57S or G58S.
The
"AS"
series
are 6.3 volts
at .4
amp filaments.
ruAJESTIC
381.
Poor
selectivity,
volume.
Many
meh
remove
the
metal
shield
on the
bottom
of
the
chassis.
Os-
cillation
is kept
under
control
by
proper
use
of the volume
adjustment.
MAJESTTC
38t
(CHASStS
380)
Dead
if
ohmmeter
applied
be-
tween
G84 rectifier
filament
and
chassis
indicates
full
scale,
8 mfd.
sec-
tion
of 8.4 mfd.
electr,olytic
condenser
block is
shorted.
MAJESTIC
'4OOA
SERIES.
"Gurgling"
variety
of hum
. Replace
6D7
detector
with new
tube,
trying
sev-
eral and
choosing best. Intermittent
re-
ception
.
.
Often
due to loose
fila-
ment
in
46,!t
or 468
ballast
tube. Hit-
ting set shows
it
up.
32
MAJESTIC
400
SERIES.
Ltrw
volume
despite
satisfactory
r.f.
pickup
.
. .
Check for
open
speaker
6eld
coil, a
common
failure.
No
signal
from
frst
57A
detector-oscillator,
i.f.
and other
tubes
alive
Test
for
grounded
i.f.
transformer.
There
should
be no read-
ing
from
control
grid
of i.f.
58A to
transformer
can. If
there
is remove
coil
from
can,
wrap
with 6sh
paper
and re-
nl-ace.
Set
completely
dead from
grid
of
the 43
output
tube . .
. Nine
times
out
of
ten
the C-bias resistor
in
cathode
circuit
is
open. Replace
with
700
ohms.
Pronounced
hunr
Look
for
shorted
electrolytic
across 43
bias resistor.
MAJESTIC
+,10, 460. Oscillation
. . .
.{lmost invariably
due to
defective 6F7,
rvhich
is critical in
this set. Motor-
boating . ..
Open I meg. resistor to-
cated
in
grid
return
of 6F7
triode
sec-
tion and shown
on
diagram
as R9.
High-platc voltage
on all tubes, no
sig-
nal
Look for
open
4l cathode re-
sistor,
which
should be
500 ohms.
I:ailure
of oscillator
to
work
Gen-
erally caused
by
poor
soldered
joint
at
third
grid
return
150,000 ohm resistor
as-
sociated with 6A7.
MAJESTIC 4mA
Motorboating
and
no
reception
High
resistance
connection between
grid
lead
of
58 I.F.
and
lug
on
I.F.
trans-
.former.
MAJESTIC
5OO
I\Iotorbo:rting
when tuned
off
res-
onance Replace
.25 nrfd. bypirss
on
6A7
and
6F7
cathodes.
Condensers
are in one
container
of four
.25
mfd.,
one
.03 rnfd.
and one .06 mfd.
capacitors.
MAJESTIC
5OO
Inoperative
over
part
qf
the
rlial
.
.
_.
. replace
50,000
ohrn
oscillator
gr.irl.
leak
connected
from
cathode
to
gricl
of
6A7. This
lesistor
often
rvill
incre;rsc
greatly
in
value.
MAJESTIC
5@.
Poor
selectivitv
.
. Drill
hole
in
top
of second
i.i.
transformer
case
and
mount
a
balancing
condenser
in this
position,
connecting
it
across
the transformer primary.
Ad-
just
for
maximum
selectivity.
MAJESTIC
500. Nothing
coming
through
tubes
ahead
of
42
.
.. Look for
()pen
coupling
condenser,
tubular
type
.05
going
fronr
triode
plate
of
6F7 to
control grid,
of
42.
Motorboating,
all
voltages
ok
Change 3rd i.f.
trans-
f
()rrner.
Trouble
is
usually
prirnary
to
secondary
short.
Set stops
when near-
b1' light
is
turned
on or
off.
.
.
Short out
a.v.c.
300,000
ohm'resistor
in
grid
return
circuit
of
6,4,7. Trouble
is
due to
over-
lriasing
of 6A7 by
surge,
paralyzing
its
action.
IIAJESTIC
520.
Replacing
25
with
easier-to-obtain
19
. . . Looking
at
bot-
to-m
oJ
six-prong
socket,
reading
clock-
wise frortl
filament prongs,
coniections
originally
are
as follows:
Filament.
fila-
T..nt,
plate,
.
diode,
diode
and
'giid.
Lnange
clrcutt
connections
so
that
the
grid
lead
goes
to
the
old
diode
prong
immeiliately next to
the
plate
while the
diode
lead
removed from this
prong
is
carried to
the
old
grid
connection. The
prongs
should now read: Filament, fila-
ment,
plate, grid,
diode,
diode.
(I.F.
175 kc.)
MAJESTIC
650
Noisy,
crackling . . .
this
can usually
be tlacecl
to
poor
connections
in
the
second i.f.
transfolmer.
A high
re-
sistance
meter
conlrected
across
the
prin-rary
with
the rcceiver
operating
will show fluctuations.
Replace
trans-
former.
MAJESTIC
Weak,
crackling
check spraj'
shield on
all tubes
to see if
shield makes
good
contact with
base
pin.
If
poor
connec.tion
is found,
a small
wire wound
.around
tube where
the base
ioins
the
glass
will
bond
the base
pin
wire
to the
shield.
MAJESTIC. No
signal
or signal
pro-
duced when
set is
jarred,
types having
speaker
mounted on chassis.
Look for
broken
lead
to
voice-coil.
Vibration fre-
quently
breaks
these.
MAJESTIC.
Models
using
pilot
as
resonance
indicator.
Set dead or dis-
torted.
Look for
open
or shorted wind-
ing
on center
leg
of indicator trans-
forr.ner
in r.f.
and i.f.
plate
ciriuits. Re-
place.
For
temporary
repair
short out
',vinding
by bridging
two
outside ter-
rninals
and usine
3.2 volt
oilot.
MAJESTIC
VIBRATORS.
Notes
on
adjustment
Loosen
screws 2
and
3 until
there
is a fairly
large
gap
between
contact points
a
and
b and
i
and
d. Then
adjust
screw I
until
the
distance
between
points
e
and f
and
g
and
h is equal.
In
other words,
see thai
the
armature
balances
equally
on
both
sides
of
the
pivot.
Now
adjust
screw
3
until contacts
c
and
d touch,
then
tighten
set
nut
Ja.
Finally
adjust
screw
2
until
there
is
a snrall
gap
betweerr
contacts
a and
b.
'lighten
set lrut
2a
arrd
the
job
is rlone.
-1
(E;;6me;;;;frrc--1
I
Cross Seclion
MARQUETTE
5t
(HEREERT
HORN)
Signals
acconrpanied
by
hissing
noise^
.
open
.01
mfd. plate
bypasi
on
12-
MIDWEST II
Poor
operation
, .05 condenser
from
grid
coil return
to
ground
omitted
in
diagram
and set, install
and realign
for
increased
gain.
Replace
the two
I
watt
carbon resistors
across
the lugs
of
the
speaker
socket with I
watt,
orange resistor is
3 meg
and blue 6
megs,
check .l mfd
connected from
their
commo4 ground
for leakage,