Sec. 1
"Cose
Histories"
of
Receiver Troubles
and
their
Remedies
PHILCO
14X,
14LZX-(Cont'd)
Inoperative
__
1)
failure
or
"open"
circuit
in
shadowcraph
(shadowcraph
(connected
in
"B"-plus
circuit
of
the
r-f
does
not
and
i-f
tubes
operate)
Intermittent
______
1)
snapped
coil
leads
at
lugs
of
01cillator
reception
coil
Insufficient
________
1)
small
antenna.
Increase
size of
antenna
shadowgraph
2)
weak
type
'44
tubes
in
r-f
and
i-f
stages
action
3)
increase
value
of
diode
detector
sec-
ondary-return
resistor
Shadowgraph
____
l)
receiver
circuits·
out
of
alignment
inoperative
on2)
defective
type
'6A7
tube
local
stations
No
control
of
____
1)
check
type
'37
tube
in
first
audio
stare
tone
Signal
drift
_____
1)
after
set
is
turned
on,
the
tuninr
of
the
station
"creeps"
for
as
long
as
30
to
60
minutes.
Replace
tension
spring
on
back
of
gang
condenser-use
new
type
Philco
spring
(part
No. 77760)
(
due
to
dial-
cueping)
Noisy
volume
___
1)
disconnect
end
of
control
that
goes
to
detector
and
from
this
detector
lead
con-
nect
a 300,000-ohm
%-watt
resistor
to
ground.
Also
from
this
lead
bridge
a
0.05
or
0.06-mfd. con.denser
to
the
dis-
connected
end
of
the
volume control.
This
removes
the
d-c
from
the
volume con-
trol
and
permits
quiet
operation
control
(
installing
a
new
control
only
a
tem-
porary
cure)
Motorboatinr
____
l)
eliminate
by
connecting
100,000-ohm
re-
1i1tor
from
first
audio
grid
to
chassis
sound,
Hum
Broad
tuninr
_____
i)
r-f
and
i-f
compensating
condensers
out
of
alignment
Whistling
__________
l)
compensating
condensers
out
of
adjust-
ment
2) move all
leads
adjacent
to
01cillator coil
further
away
from
it.
PHILCO
CT-14
Auto
Radio
Weak
reception
__
})
check
alignment-especially
of
antenna
1tction
of
tuning
gang.
To
improve
per-
formance,
move
the
lead
that
goes
from
~rst
grid
section of
gang
to
the
coil
away
from
all
other
leads
and
the
chassis
PHILCO
TH-14
lfodulation
hum
__
})
replace
conuenser
No.
1!
with
a ~-mfd.
at
hi,:h
volume
electrolytic
unit
PHILCO
15
Inoperative
________
l)
tuning
meter
No.
37
"open"
(indicated
by
narrow
shadow)
2) check
condenser
No.
13
(0.25-mfd.)
from
first
detector
plate
return
to
,:round
for
breakdown
3)
check
condenser
No.
16
(0.05-mfd.)
from
first
i-f
plate
return
to
ground
for
break-
down
(3-mfd., 0.5-mfd., 1-0.015-mfd.,
and
1-
1-mfd.)
4)
check filter
condenser
block No.
3S
5)
"open"
primary
of
input
transformer
No.
56
~) check No.
25,
couplin~
condenser
con-
nected
from
oscillator
plate
to
coil
(Cont'd)
PHILCO
15-(Co11t'c)
Intermittent
--1)
replace
the
200-ohm
oscillator
cathode
reception
resistor
and
the
0.09-mfd.
by-pass
con-
denser.
Use
a 0.1-mfd.
condenser
to
re-
place
the
odd-size 0.09-mfd.
unit
2)
replace
coupling
condensers
No. 44
and
No. 49 (0.01-mfd.
each)
in
first
and
second
a-f
stages.
Although
these
con-
densers
may
test
O.K.
it
is
best
to
re-
place
them
Distortion,
_________
})
connect a 0.25-rneg.
resistor
acro11
the
normal
volume control,
and
a 0.002-mfd.
condenser
between
the
plates
of
the
power
tubes
Weak,
"tinny"
at
hirh
volume
2) check condensers No. 48
(twin
0.25-mfd.)
for
breakdown.
Common
ground.
Ont
goes to
filter
resistor
of
first
audio
plate
supply,
the
other
to
filter
resistor
of
all
audio
grid
biases
3)
bn,akdown
in filter condenser block
No.
33
between
sectio11s.
Capacities
3-0.5-
mf
d.,
1-0.015-mfd.,
1-1-mfd.
4)
check
push-pull
input
transformer
No.
56
for
breakdown
(indicated
by
"fryin~"
noise)
Audio
whistle
----1)
replace
both
'47
push-pull
output
tt1b11
check
for
loose shield
cans
on
r-f
and
i-f
transfort.:.ers
Squealing,
--------1)
Noise.
Squealing
------1)
(intermittent
and
steady)
replace
condenser
No.
12
(0.09-mfd. con-
denser)
from
screens
to
ground.
Con-
denser
may
test
O.K.
but
may
be
inter-
No
:r;ero
Yolume
__
at
any
setting
of
volume
control
mittently
"open"
.
2)
replace
condenser
No.
13,
-(0.25-mfd.)
from
first
detector
plate
returns
to
ground.
Condenser
may
test
O.K.
but
may
be
intermittently
"open"
3)
replace
condenser
No.
31
(0.05-mfd.)
from
first
i-f
AVC
filter
resistor
to
ground.
Condenser
may
test
0.K.
but
may
be
intermittently
"open"
4)
replace
condenser
No. 26 (0.06-mfd.)
first
i-f
plate
return
to
ground.
Con-
denser
may
test
O.K.
but
may
be
inter-
mittently
"open"
"open"
A
VC
Condenser
No. 42 ( 0.00011-
mfd.)
connected
from
volume
control
to
rround
"Shadowgraph"
--1)
does
not
indi-
cate
on
weak
signals
replace
first
detector
and
i-f
tubes
Tuninr
con-
______
l)
faulty
spring
used
to
hold
drive
cable
under
tension.
Replace
with
imprond
spring
(part
No.
7776)
denser
slip-
pinr
PHILCO
16,
UB,
16X, 16RX-(C-O<l.es 121, 122)
Inoperatin
_______
l)
open
circuit
in
tuning
meter
No. 48
2) check
condenser
block No. 62. Common
goes
to
Cc:'.n;
condenser
A
(2-mfd.)
to os-
cillator
plate
filter
resistor;
condenser
B
to
tuning
metet';
condenser
C (0.6-
mfd.)
to
first
a-f
plate
supply
filter
re-
sistor;
condenser
D (0.5-mfd.)
to
screen
supply
of
first
a-f
tube;
condenser
E
(1-
mfd.)
to
screen
grid
supply
of
first
de-
tector
and
i-f
tubes
3)
check
condenser
No. 94 (0.05-mfd.)
from
first
detector
and
first
i-f
plate
supply
to
ground.
Faulty
condenser
here
indi-
cated
by
narrow
shadow
on
tuning
meter
4) check
for
breakdown
between
Hctions
of
condenser
black
No.
62. (Capaciti11
2-2-mfd.,
2-0.5-mfd.,
1-1-mfd.)
(Cont'd
over)
153
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