Technical information

@
RADIO
RETAILING'S
,,,
e&i@
G.E.
A-85
I-orv
volrrnre or no reception
check
voltage across 3000 ohm
6rst
audio
cathode
resistor.
If less than
2
or
3 volts
replace
electrolytic bypass-
ina'
this
section
with
5 to
10 mfd.
25
volt
unit.
e.
E. 16
Static
but station
cannot
be
tuned
in.
.
Shorted condenser
in sentry box
un&r
6A8 tube.
To
replace,
unsolder
all leads
on sentry box,
remove front
dial
screws, lift
up
dial
assembly,
pull
out
band shaft,
remove
front section of
sentry
box from
bottonr.
G.E. A87
Weak
or
dead .
. . check
for
shorted
.05 condenser
and
charred 2000
ohnr
resistor
insicle
secorrd i.f.
can.
G.E.
Egr,
E95, EtO!, ElOs, Er06,
i155
High noise level break
cathod€
connection of 6K7 first i.f.
and bias
through
l0,flgg
oltr half watt resistor.
Bypass rvith
.05 mfd.
condenser.
G.E. G97
Pushbuttons
stick
at either
end of
dial. .
.
Loosert tetrsion
spring
fast-
ened
to
latch
bar at the
end of the
switch.
GE IO5
Weak, no
colorama
tuning.
',laa" \74...tiC^.
Re-
6. E.
r05
Off
calibration
.
.
check
afc.
617
and 524
tubes
before
adjusting
trimmer
condensers.
GEJl00,Jl05.
10 nrike capacitor
with
yellow
lead to
lug on volume
control
opens, causing
oscillation
. , . When
re-
placing
watch
polarity
as
ground
is
posi-
tive in this
circuit.
GENERAL ELECTRIC
FI07,
FI35
Loud
noise
when
station
is tuned
in
by
nreans
of buttons.
Contacts
of
switch
not
opcning
in
proper
se(lucnce;
cellter contacts
(motor)
shorrlcl open
first,
contacts
farthest
fronr arnrature
(A.F.C.)
second, and contacts
nearest
armatures (silent
tuning)
should
open
last.
Skipping
of stations.
Backstop
for relay
armature should
be adjustecl
so that a
potcntial
of
4.5 volts is suffi-
cient to snap relay closed. The
back-
stop
must
make
positive
contact rvith
arnrature when relay is open. If the
relay
will
not
close at
4.5 volts
and
still
r-naintain
proper
travel and
se-
(iuence,
weaken the spring
holding
armature
open.
Hunr
when
relay is energized.
The
pole-piece
of the
relay
is divided
to
f orm
two
semi-circles.
The relay
arntature should touch
only the
semi-
circle
nearest the motor
shaft.
There
should be a
l0-mil clearance
between
the other segment
and relay armature
rvhen
the
relay is energized.
Bending
the entire armature
support
may correct
this
condition otherwise
the
pole-piece
should be
filed down.
Hum may also
be
caused
by a bump
on
the segment
with
which the arrnature
comes in contact.
This may be
removed
by
filing.
Be
sure
all
filings
are
removed after ad-
justments
have been
made.
After
any adjustment on
relay,
se-
quence
in which contacts
open should
be
checked
to
open in
order
indicated
above.
lllotor hums but
no torque.
Shorted
motor capacitor,
1000 mfd.
12
volts, A.C. working
voltage.
Motor inoperative.
Center
con-
tacts on
relay not
making
good
contact.
Defective motor reversing switch.
Cold solder
connection
on motor re-
versing switch.
Open or shorted
coil
in motor, char-
acterized
by
no torque
or. low
torque
in one direction.
No
action
when
button
is
pressed.
.
Push button
escutcheon
grounded
to chassis of set.
This trouble is usu-
ally
caused
by control shafts
touching
escutcheon.
Centering chassis
in cabinet
or
placing
fibre sleeves on
shafts will
remedy this
trouble.
This trouble
is
characterized by the
relay remaining
closed.
Motor scans but
does not stop at
desired station. Contacts
at the
rear
oI
the
button shafts do not
make
good
contact.
Adjust
by bending contacts.
Motor
scans but stops
at wrong
sta-
tion.
Contacts
at
the
rear of the button
shafts
touching,
or, shaft
is touching
contact.
Adjust
by bending contacts.
Motor-boating when
station is
tuned
in
by
means
of buttons.
A.F.C.
out of
line,
acljust
hex nut on A.F.C.
transformer,
until
"puil-in"
is
equal
on
both sides of station
carrier.
Belt
slips.
Loosen 2
screvvs
holding
motor
to support
and lift motor
higher,
tighten screws.
Low
freouencv
stations weak
or
irr-
audibli, higier frequencies
normal.
.
Shorted 580
kc.
padder.
Excessive hum, volume
control
off.
. . .
Reverse
voice coil
leads
on speaker.
Make
sure
both contacts
for
olates
of
rectifier (523) are making
good
con-
tact.
GM 50 SERIES.
Volume
weak,
plate
voltage low
Look
for leakin5
or shorted
r.f.
plate
condenser. It
is
generally
the
top
one
in the
3-pile
as-
sembty that
goes
bad so don't
unsqlder
the others
until the top one
is tested.
GE
M106.
Sensitivity
poor
on short-
waves all or
part
of
time
.
. . Check r.f.
and
detector
condensers by-passing coil
returns
to
ground.
Dial slips on
f
ast
speed knob setting . Remove
chassis
and
bend
down
three contact springs
on
tuning
knob
shaft.
GE F.I07
For
intern.rittent
operation
of
this set
check the
pilot
light
socket
and bracket
assembly
for shorts.
GE F.I07
Unsatisfactory
operation
of the auto-
nratic tuner
unit
on some
of the earlier
rnodels
is caused
by a slipping
drive belt.
A small
hole
drilled
through
the
back
corner
of
the
motor
base
plate
and
a
tapped hole
into the
chassis
will
enable
a
small screw
and
sPring
to be
used
as a belt
tighting
unit
to
secure the
proper
tension.
GENERAL ELECTRIC
II07.
Stuttering,
volume same as
when
avc
tube is
pulled
out . . . Replace C38, Czl,
Cl9, C36, C35.
These
are, in the same
order,
10 mikes
at
200 volts,
.5 at 6fi),
.1 at 600,
l0
at
400
and
10 at 400.
Trouble is
due
to high resistance
short
between capacitors.
cE I
rE.
Continual
frying noise
with
volume
control either at
minimum or at
maxi-
mum
.
Frequently due
to induction
from the a.c.
transformer leads running
under the resistors.
Using
an
insu-
lated screwdriver,
move
the
leads down
or out until
the noise
stops.
Glf,
120,
130. Hum,
reception
nor-
mal
. . Reptace .1 mike condenser lo-
cated under a.c.
terminal strip.
G.E.
A-125
High
sensitivitv,
crackling,
llo
av(.
shortecl
.05 rufd
on
screen
of
0K7
avc
arnplifier
stage.
This
is
a
200
volt
unit,
replace
rvith
lrigher
voltage
rating.
G.
E.
Et26
Inscnsitive
look
for
shortecl
.0.i
nrid
bl.pass
in plate
circuit
of
61.7
nrrxer.
.{lso
burned
2200
ohm
rcsistor.
inside
first
i.f. transfornrer.
GE
FI35
Aututltirlie
tttnirrq irru1,.'r:rtirt.. rrr:rtr-
rurl
ttttring
nttlnral t:rp
rt'lirl
()l
,lcit
flont
sitle,
looking
lrt clurs.is
Ir'orrr
reiLr.
If
still inoperativc.
clc:rn lrrrd ad-
jrrst
t-elrtv
c()ntact:.
G.E.
r55
\{otorboating.
ltornral
operatiorr
tor
a
few
rninntes then a thump
follorved
by
poor
quality.
Look
for
poor
ground
connection of triple
section
con-
denser
in
corner close to
6L6 tubes. This
connection
is under
a
group
of b1'pass
condensers and
is
s'elded
instead
of
soldered.
25