Technical information

O
RADIO
RETAITING'S
".
ehuia
GRUNOW
8A
Low volume,
high
plate
current
on
output
tube
.
Low
resistance
short
of the
output tube's
bias resistor
due
to
leakage from
6lter
condensers
through
fibre protective
covering
to close-fitting
can.
GRUNOW
IIA
Distortion
a iter 1.5
nrinutcs
onera-
tion
clrt.ck
coulrlirrg
corr,li,rrrer-
betrveen
85
seconcl
cletector-and
76
push pull
clrives.
GRUNOW llA.
Oscillation . .
Drill
out rivet
used for mounting
shield
and
socket of 6C6, replacing
the rivet
with
a
6/32 brass
machine
screw.
The
placing
of a soldering
lug under
this
screw on the underside
of
the chassis
and
grounding
of this lug
to chassis does
the
job
without disfiguring
the radio.
GRUNOW
IIG
Dead
0.1 mfd.
tubular
con-
denser,
(part
No.
n,13S)
bypassirrg
screen
of 6K7
in
first I.F.
stage,
shorted.
GRUNOW
IIG
Dead
Check
.lmfd
screen bv-'
pass.
Replace
with 600 volt
type.
GRUNOW
5OO
Although
not
shown
in
the factory
diasrams
some of
these
sets have
a hum
bucking
coil
in
the
speaker.
When a
set
has no plate
voltage
check
the
speaker
windings
as sometimes
a
flash
occurs
between
the
field
and this
wind-
ing.,
destroying
the leads
to the field
coll,
GRUNOW
542
Inoperative
otr shrrrt
uaves.
broatl-
cast nornral
touch colltrol
glid
of
6Q7 lvitlr
su itch in
slrort
n.ave
posi-
tion.
If
no signal,
r'eplace
.02 nrftl.
l-rlpass
{ronr
otle l.s-
oi
su.itch
tcr
r:rouncl
l'ith 600 r'trlt
tr'pc.
GRUNOW
660
Mushy
reception
.
.
. .01' nrid. coupling
condenser
between
plate
of 75
anrl
grirt
of
42
leaking.
Resistances
as higli
as
5
to
l0
megs
is sufficient
to impair
reception.
Replace
with
600 volt
typc.
GRUNOW
560, 66t, 662
Weak
or no reception
. test 0.02
mfd.
condenser, bvpassing plate
supply
of 6D6 r.f.
stage, for short.
2,000
ohm,
d--watt
resistor in
plate
circuit
of same tube
also likely damaged if
condenser
defective.
GRUNOW
660;661, 662.
Bad dis-
tortion
when volume
is
advanced . . .
Suspect high resistance
leak
in .01 audio
coupling
resistor,
sometimes
of the or-
der of 5 megohms.
A neon tester
will
catch
this trouble
but an ohmmeter
will
frequently
pass
it
up unless used
on an
extremely high range.
GRUNOW
90t,
902
This
receiver
enrploys a
687
in an
unorthodox
a.v.c.
circuit.
Special ruanu-
facturer's
instructions
must be
follorved
in
order
to correctly align
the
set.
In
adjusting
the
a.v.c. trinrnrel
on
tlre
underside
of
the
clrassis,
located
be-
tween the tu'o
pairs
of i.f.
trinrnrers,
the
correct adjustnrent is
betrr'een
tlrc
two
peaks
obtained
on
the
output
meter rvhen
the a.v.c.
tlintnrer
is
ttrrnetl
counter-clockwise
fronr the
nraxiurunr.
GRUNOW
1101. Volume
on
full
all
the time,
no control
Replace
re-
mote control
cabte or remove short be-
tween
blue wire and
metallic
shield
over
black wire.
(lF
262 kc.)
GRUNOW II9I
'funing
itrtlicatol
tulrt.
slrolt livtrl
,open
platc
cilcuit
oi tlris tubc:urd irr-
sert
50,0(r0
ohrrr
I :
\\
att resistor'.
'L'his
lieeps
plate
voltage xt safe
\,:rlue.
GRUNOW
il9t.
t29l
Low
volunte,
r'olumc
contr-ol
inefTec-
tive
except
in
extrerne
off
position
high
resistance
short
in
control.
Oil
fronr
shaft has
leakcd
on element.
GRUNOW
il9t,
t29l
Set dead
but tuning
eye
operates
. . .
Check for
open 205
ohm
6F6
cathode
bias resistor.
.
For
high
pitcled
tone
check
speaker
terminal
strip.
One
lead
from
output
transformer
broken.
GRUNOW
I29I
Part
of dial
dead
dial shorting
or-re
lug
of volunre
control.
GRUNOW
I29I
Itrtelntittertt
oscillation lLtrtl lli)t()r-
boating
..
()l)en
screell
bypass
ol
6J7. ltcplucr
nith .1
nrirl.
-l()()
r'olt
ull
lt.
GRUNOW I54I
Dead,
except ior stroug locals
look for
open acoustic filtel
choke irr
plate
circuit
of 6R7.
6RUNOW
t937,
t5 TUBES
Peculiar
hum
which
develops
after
few nrinutes
of operation
. connect
shell
of large
speaker
to
ground.
HALSON
HALSON
AC.DC
.
Difliculty
in
obtainiug
dial
lights for
tlrese
and
similar
sets
using
the pilots
in
series
with.
tube
filaments
.
Shunt
25-ohm
resistor
across pilot
socket
and
replace
bulb
with
6-8
volt pilot.
Set
will
thereafter
continue
to operate
even
though
pilots
burn out.
HALSON
N.S.4O
Burns
out
2525
alnd
pilot
light .
replace 2525 socket
which has blown
over
to
ground.
I'ilot light is the
2.5
volt variety.
HOWARD
HOWARD 67
Low
volunte
and
poor
qualitv
High resistance
leak in 0.25
condenser
by
passing 6F5G
plate resistor to
glorrrtd
is
mosi comlnon
cattse.
HOWARD
67,
77
Weak . .
.
look
for
short
between
positive
leads
of filter
condenser.
This
shorts speaker
field.
HOWARD 2OO
Dead
. look for
shorted
.1 mfd
200
volt conrlenser
front
6K7 screen
to chassis.
HUDSON
'3+
HUDSON.
Noise suppression
. . . Install
a dual condenser
on
the
gen-
erator, one directly on the
temperature
indicator
at the radiator,
another
directly
on
the oil
gauge
connection
at the
bottom
of the motor
pan
and
also one
on the
gas gauge
directly on the top of
the
tank.
This
can be reached back
of
the rear seat
as there is a
door for
access. Also
use condensers in
the dome
light
lead and coil supply lead
right at
the
coil. It is also frequently
necessary
to shield the high
tension
lead
frorn
the
coil right
up to the fire wall.
And the
low
tension lead from
coil
to distribu-
tor should
be removed from
the
spark
plug
duct
and
shielded.
HUDSON
TERRAPLANE
SETS
When
installing
auto
sets in this
car
an
annoying
intermittent
buzz is
often
present
while
the motor
is running.
Motor
noises
are carried
and radiated
by the
gas
line.
A condenser
from
the
gas
line
to chassis
would
not remove
the trouble.
.
A
satisfactory
solution
is
to
ground
the
gas
tank
as a fabric
insulates
it
from
the hanger.
An
easy
way
to do
this
is
to wrap
a
piece
of
copper braid
around
the insulating
fabric
and clamp
the
tank
back
in
position.
INTER
OCEAN
P.7I
Weak
erratic.
. Open
.l
mfd
condenser
fronr
screen
of 24
tube
to
ground.
INTERNATIONAL
INTERNATIONAL
J.
Hum
Test
for
defective
resistor
connected
to
plate
of second
detector
24
and. in
series
with
60,000
ohm
resistor
to screen
oi
35
r.f.
tube.
Replace
with
500,000
ohms if
defective.
INTERNATIONAL
KADETTE.
\roltages
normal
but no reception
Insulating
washers
between gang
con-
denser
and
chassis
often
slip,
allowing
condenser
to short.
Loosen
screws,
re-
set u'ashers
and
tighten.
27