Technical information

I
RADIO
RETAITING'S
",
"/ruifu
PHILCO
TI.
Set blows
fuses
and
vibrator is found
to
be ok
.
. . Check
for
short between
speaker field housing
and on-off
switch mounted on volume
control.
Tape
section
of
field
close
to
volume control and
also cover switch
assembly
with
insulating
material.
PHILCO T.I I
Boonrv
torre replace 0.1 nr.f.d.
tone control
condenser with
.01
m.f.d.
PHILCO CTII
Noisv, unstable
. .
. this auto set ha
trvo transformer
cans
in
the center
o
the
chassis held in
place
by springr
rvhich in
time
rveaken.
Insert
lugs
under
the nuts
on top of cans and
bond
tc
chassis rvith
flexible
u'ire.
Connectior
to chassis
can
be rnade
at
point
wherr
gang
conclenser is
glounded.
PHILCO I2X
I{igh
pitched
wl.ristle
shorten
twistecl speaker
leads
as much
as
possible.
PHTLCO
t4,
9l
Volume
control
noisy,
installing
a
new
control
onl_v tenrporary
cure
Discorrnect
the
irrd
of the
control
that
goes
to
tl-re
detector
and
frorn
this de-
tector
lead
connect
a 300,000
ohm.
4
watt
lesistor
to
grourrd
as
shown
in
the
diagranr.
Also
from
this
lead
bridge
a .06 mid
conclcnser
to the
disconnectid
end
of the
volurne
control.
This
re-
moves
the
cl.c.
f rorn
the
control
ancl
permits
quiet
operation.
cloth covered
wiring
. . , Substitute
6A7
for
36, employing
new circuit
dia-
grammed.
The
same
oscitlator coil
is
ug9d, but
the
various
windings
erpployed
differcntly.
Slight
retrimming
-of -all
condengers
associeted
with
circuit
is all
that is necclsary
whon rcvamping
has
been donc.
PHILCO
l,t
No
control
of
tone
test
37
first
audio
in tube
tester and
by substi-
tution. In
many
cases this
tube
is
at
fault
and not
the tone
control.
PHILCO
15.
Cuts on and
ofr
.
Replace
rcsistance-condenser
combiua-
tion
No.
24
on schematic.
This
is the
cathode
resist4ncc
and bypass.
Use
200
ohms
and
.l
mike.
PHTLCO
t6
Bad
frequency
drift
defective
trinrnrer
on
third i.f.
transformer.
Re-
placc
rvith
new
transformer.
PHILCO
f6. R.f. dead:
i.f. ok.
.
. .
Generally
caused by
ground
of
wire from
first
section of
condenser
gang
being
pulled
too tight
against chassis. Dead,
no i.f.
. . .
Checking from
grid
cap
of
77
tube in
right hand front corner,
audio
squeal
showing a.f. ok, i.f.
transformer
first facing
front
of chassis
grounded
high
voltage
lead
(black
wire). This
does
not affect
audio. Sometimes the
compensators
in top of i.f. can
ground
to
can.
Scale dead
from
11
to
26
mc. . , .
Replace
condenser
from lug I
on bottom
of wave
switch to
ground
marked
with
orange
and
yellow
dots with one
of the
tug
type
(value
700 mmfd.).
This is.due
to
poor
connection
internally
in
pigtail
condenser,
which
stops oscillation.
Hum
in
earty
series . ,
Due
to a.c, switch
jumper
from
switch through
terminal
lug mounted
on condenser
at back of
set.
Use shietded
wire,
grounding
the
shield.
PHILCO
I6X
Intermittent
fading
.
secondary of
first r.f.
transformer
has
high resistance
connection.
PHtrco
r8
Dead check
tone
control con-
denser for
short.
PHILCO f8. Intermittent fading
.
. . .
Primary
of
first
i.f. transformer
opens
up.
(I.F.
260 kc.)
PHTLCO
t8
The
tone
control condctrser
slrorting
is
frequently
the
cause of
a
deacl sct.
PHILCO
f8.
Shadow indicator
ex-
tremely
wide and no
signal
.
. . Volt-
ages
are
usually all
ok
in
this condition
and the
troublc
is
probably
shorted
trimnrers.
Bend
plates
up and
insert
larger
insulating
washers.
PHTLCO
l8
Dead
on lorv frerluency
end oi
dial
.
Checlt oscillator
coil for irrct'easc
iu
resistarrce
through
corrosion.
PHTLCO
t8
Oscillation
over
entire
dial for
re-
nroving
grid
cap
on 78
i.f.
set
returns
to nornral
connect
.005
mfd.
300
volt
condenser
from
center
lug
of 3615
AA
nal.l-o\\'
bakelite
condenser
to
ground.
PHILCO.
lE.
Cuts
out for
short in-
terval and
then resumes
ptaying
. . .
Examine
a.v.c. coupling
condenser
for
leaks
or broken
wire connection
in
bake-
lite case, causing
it
to make
or
break
contact. Tape
wooden
or rubber
handle
of screwdriver and
tap all
bakelite
cased
condensers
white set is in
operation,
note
if volume changes.
Where condensers
are faulty
the
pitch
is usuatly
melted
through
the connection hole.
PHILCO
t9
Dead
check 15,000
j
watt re-
sistor on
the
con<lensor block.
Reolace
u,ith l
rvatt unit.
PHTLCO
t9
Dead,
voltages
check
O.K.
nreasure
the 15,000
ohrn
j
watt
resistor
on
the resistor
ancl condenser
block.
This
ofter-r
changes
value. Replace
rvith I
watt urlit.
PHILCO
19.
Set
dead,
voltages
ok.
Check
15,000-ohm,
l-watt
re-
sistor on resistor
and
condenser
block.
Apparently
it
changes value
badly when
current
is applied.
Replace
with 1-watt
unit.
PHILCO
19,
E9.
Intermittent
opera-
tion
Try new
oscillator
tubi,
or
change cathode
bias resistor
from
15,000
to 10,000
ohms.
Examine
mica
of oscil-
lator
high-frequency
compensating
con-
denser.
Il
cracked replace
as
moisture
sometimes
gets
in
and
stops
operation.
(I.F.
260 kc.)
PHILCO
19,
89. Intermittent
cutting
in
and
out,
no
voltage
changes
noticed
. Replace
condenser
number
30
(3903T)
and number
27
(3903AB).
They
can be
bridged
with
a 600 volt,
0.5.
PHILCO
t9,
89
Internrittent
or
weak
on
high
fre-
quency
end
of
dial
. . . examine
the
nrica
between the plates
of the high
frequency
oscillator trimmer.
If
small
cracks
are visible
in mica.
reolace
with
new
nrica.
PHTLCO
t9-89
Intermittent,
returns
to
nornral
rvhen
line
switch
is
cut on
and
off
.
. re-
solder
oscillator
cathode
bypass
con-
denser.
Poor
joint
causing
intermittent.
PHTLCO
20
Intermittetrt
or uoisy,
okeh
when
antenna
is connecte<l
to second
r.f.
grid
lrig-h r.f. rcsistance
in
rrlate
coil
of secorrrl
r.f. .tage.
PHILCO 14
(Early).
36
autodyne
first
detector
does not oscitlate
stably at
lower frequencies,
changing
of
oscillator
coils and
bias resistor
does not afiect
permanent
cure.
Nor
does
replacement
of
tubc, mica in
tuning
gang
trimmers
or
Origrnol outodyrr
'06
ac/
39