Technical information

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RADIO RETAILING'S
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A.K. 46
Distortion
.5
mfd
of first
original
AK
37-60.
New, double-spring contact
arms are available at
the
factory
and make
it
ururecessafy
to change entire
volume
con-
trols
rmless the
wire
is
shot.
Clean
the
winding with alcohol.
AK
37, 40,
41,
12, 43, 44,
53,51,
55,
55C,
60
Installing
volume
control strips
Connect
replacement
strip
across
ll0
volt, a.
c.
line
in
series
with a 75-uatt
lamp
for one minute.
This will
make
the
strip
pliable
so that
it
can be in-
serted
in
the
control
shell
without
breakage.
AK 37, 38,
40, 42.
Wire
on
flat-
strip volume
corrtrol
breaks
Remove
control,
solder break
and bend flat
strip
in opposite
to
original direction
so thit
contact arm
rides on unused ,urface.
AK 37,
38, 40, 42.
Use of
a
I
nrfd..
400
volt condenser
between
the filament
of
the 280
where it connects
to the first
choke
and
ground
increases
pep
and reduces hum.
Try it
next
time it is necessary
to rip open
one
of
the cans.
AK 40,
Oscillation
during warming
up
period
.
Shunt the
secondary of
the
first
a.f. transformer
with a
250.000-
ohm
resistor.
AK 40.
When biasing resistor strip
under
terminal board
is defective and
original replacements
can not
be
ob-
tained use
one
750
and one 3,500-ohm
AK 40.
Fading
and low volume, es-
pecially
where
26's
are old . . .
Put
on
additional filament leadr
from
power
pack
through
a hole drilled in
side
of
pack
case to filament
lugs
of
first r.f.
socket.
This will lower drop in leads,
raise
voltage on
26's
and
improve
per-
formance.
A-I(
&,
12.
Wcak
reception.
May
often
be
pepped
up
by
reptacing
de-
tector
resistor,
which is
of
gtass,
grid-
leak
type,
with
a variable
unit taken
from
an old
B-eliminator.
AK 10,42.
Excessive
hum . . . Look
for
poor
connection
between
ground
ter-
minal
under resistance
strip in
power-
pack
and
wire
going
through insulating
compouhd
into
pack.
AK 40, 42,44,46,
53. To check or
re-
place
filter
condenser
sections .
Look-
ing from front,
panel-side
of set, block
is
at
extreme
right, next to choke as-
sembly. Three leads connect
from block
to chokes,
blue,
yellow
and white. Stick
a
pin
into each lead so that
it
contacts
the wire and
with an ohmmeter
clteck
from
pins
to
ground
for short.
After
locating defective section
clip its asso-
ciated lead close to block,
leaving
rc-
mainder of
lead
attached to
choke
asser{rbly.
Attach
positive
side of
re-
placement
cartridge
type electrolytic
to
lad
and
ground
negative
to chassis.
AK
55, 60.
Motorboatrng, all
parts
in
detector and a.f. check ok
and all con-
densers working
properly
. Make
careful
resistance check of all choke
coils in
r.f. system.
A
short of
only 2
ohms
in
just
one choke rvill cause
this
trouble.
AK
6OC
(First production
with
siugle
vol-
ume control.)
Loses volume after
warm
up
replace
65,000
ohrn
resistor
between B
plus
and r.f.
screens.
^.K.60
Inoperative . .
.
1050 ohnr flat rvire-
wound
resistor located
under red
and
'yellow
resistor
mounting open. Cut
lead where it
solders
to
condenser ter-
minals. Replace with
I watt carbon
unit soldered from this
condenser to
ground.
AK
60,
60C.
Low
Plate
voltage,
noisy
reception,
little
volume
. . . Check
two
a.f.
glid
resistors.
One
should
be
40.@0
ohms,
the other
65'000.
TheY
have a
habit
of
droPPing
in value.
AK 61.
Noisy
after
about
2,000
hours of
use
Three fitanrent
resistors
wouud
on
iron strip
conrntonly
overheat,
buru-
ing insulation
and shorting
to iron.
ATWATER
KENT
55
I)istortion
on iocals, even rvith switch
in
local
position
.
remove
low side
of
volume control lead from cathode
at
cathode condenser terminal
and connect
to
ground.
A.K. 55
fnoperative.
Look for
a small
piece
of broken antenna
wire wedged
in
between
antenna
.terminal
and
chassis.
AK 55.
Weak and distorted reception
.
. .
Check
two resistors across
speaker
field.
Center tap between them
goes
to
center tap
of a.f. input transforrner sec-
ondary. Value
of
resistors
should be
9,500
ohnrs.
AK
itc
Intetmittent operation,
conponent
parts
apparentty
ok, voltages nonmal
.
. .
Chcck
secondary of
output trans-
former
by temporarily
substituting a
magnetic speaker.
.Troublc
frequently
does not
show up on continuity tesL
Disconnect
voice-coil whilc making
this
test.
A.K.
206,
376
Incorrect
dial
calibrations
at the
lorv
frequency
end.
. . . Readjust
broadcast
trimmer
located
at rear
of chassis.
This
adjustment is
rather
difficult
to
find on the
chassis.
replace
condenser
from B
plus
end
audio
plate
resistor.
The
condenser
is
in
a
oack.
J,7--^JD
\, ItnE
a:i7,rn
T!-lrnAtt9
ar=-42
ItF"
-
Servicemen
know
that
with
Centralab
parts
they
can
do
a
better
replacement
iob
on
any
and
all sets.
So
when the
going
gets
tough
get
in touch
with
your
Centralab
iobber
al once.
@
CERAMIC
CAPACITOR
%
Wave
Band
Swilch
Div.
o( Globe
Union Inc.
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