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maintenance
CONTROL
ADJUSTMENTS
a)
The
INPUT
LEVEL ADJ.
control
I*
Intended
to protect the
speaker system from
"blasting"
should
someone
turn
the
preamplifier-control
unit level
controls to
full,
by
per-
mitting
you
to
attenuate
the preamplifier
output
signal
by
any
desired
amount
at
the Input
to
the
power
amplifier
where
It
can
not be "fiddled" with.
Start
by
setting
the
INPUT
LEVEL maximum
cotnter-elockwise
(maximum
at-
tenuation), using a screwdriver. Set
the
LOUDNESS
con-
trol
on your
preamplifier
to the
maximum
clodkwlse
posi-
tion
and
the
LEVEL
control at the
midpoint
of
Its
range
of
rotation.
Turn your
phonograph
on and
play
on average
orchestral record.
Then
slowly
ortate the
INPUT
LEVEL
ADJ.
control
clockwise
until
the
music
Is
at
normal
(or
concert)
listening level.
This
completes
the adfustment,
which need
not
be
repeated.
b)
ON-OFF
SWITCH:
Should
be
used
in
ON
position
when
unit
Is
used with
a preamplifier.
It
may
be used
as
a
power
on-off switch
when
the
amplifier
Is
accessible.
TROUBLE-SHOOTING PROCEDURES
Your
ampllflershould require
little
service
except
for
nor-
ma! tube replacement.
We
recommend no
substitutions
for
the
tube
types
used
In this
amplifier.
The
ELM,
and
EZ81
types are distributed
natlonallyby the
Amperex
Elec-
tronic
Corporation (230 Duffy
Ave.,
Hlcksvllle,
LI.,
N.Y.)and
Mullard
Ltd.
(International Electronics
Corp.,
81 Spring
St.,
N.Y.
12,
N.Y.)
If
necessary, replace-
ments
can be obtained
directly
from
EICO.
To
facilitate servicing,
remedial
and
trouble-shooting pro-
cedures
have been
provided
In
the
TROUBLE
SHOOTING
CHART
that follows.
A VOLTAGE
AND
RESISTANCE
CHART
Is
also provided
as
an aid
In
locating defective
components and
to
permit
a
careful,
stage-by-stage
check
of the amplifier.
DC
operating voltages are given both
at
no
signal
and
at
a
signal
developing
14 watts output
as
well
as
the corresponding
Ike
signal voltages.
To
Isolate
the source of unusual
hum
or noise
in
your
system,
first
turn off the
AC
power and
then
unplug
the
audio
cable
connecting
to
the amplifier
input.
Then
turn the
AC
power
on again
and
note
whether
hum
or noise has
decreased.
If It
has,
the
fault
is
in
the preamplifier or associated
equipment and
measures should
be
taken
to
correct
It
os
described
In
the service notes
for
these
units.
If
it Is
de-
sired to
provide a good
building
ground
for
your
entire
system, run
a
lead from
under speaker connection
terminal
"G"
to
a
cold water
pipe.
Do
not
connect such
a
ground
wire
to
other
components
in
the system.
If
the trouble
is
no
output
or
low output
and
the amplifier
is
suspected,
check
AC
signal
voltages
starting at the
In-
put
and working
step-by-step
toward
the output,
using a
sine-wave audio
signal
generator
and
a
VTVM.
Set the
Input signal to
1
volt.
The
corresponding
grid
and
plate
signal
voltages
for
this
input
are
indicated
on
thesehematic
diagram.
This
procedure should
suffice to localize the
defective
stage.
If
the trouble
Is
at
excessively
distorted output,
try
tube
replacement,
signal
tracing or
precede
directly
to
voltage
and
resistance
measurements.
When
the defective stage
Is
localized,
precede
to
a
re-
sistance
and
voltage
check
of
the stage, using the
data
in
the Resistance
and Voltage chat.
Disconnect
the ampli-
fier
from the
power
line
and
discharge capacitors
prior
to
making any
resistance
check
or
removing
the
ELM
output
tubes.
Do
not
turn the
amplifier
on
with
any
of the output
tubes
removed.
"
CHICKING
A
TYPICAL TUBE
STAGE
1.
Check
tube.
2.
Check
plate
and cathode
resistors.
3.
Check
coupling
capacitors
for
leakage
or
short.
4.
For output
stage,
check
dc
resistance of transformer
windings.
5.
Check
grid
leak
resistor
for
open.
6.
Check
cathode by-pass
capacitors
for short.
7.
If
no
or
low B+ voltage on
tube,
check
decoupling
path
for
open
or defective RI4,
and
filter
capacitor,
C8
for short.
8.
if
wiring
and
circuit
components
Including the tube
check
O.
K.
and B+ voltage
is
excessive,
check
the
de-
coupling path
for
short or
defective R14.
SERVICE
If
trouble
developes
in
your
instrument
which
you can
not
remedy
yourself,
write
to
our service department
listing
all
possible indications that
might
be
helpful,
if
desired
you
may
return the
instrument
to
our factory
where
It
will
be placed
In
operating condition
for
$5.
DO
plus the cost
of
parts
replaced
due
to their
being
damaged
In
the course
of construction.
NOTE:
Before returning
this unit,
be
sure
all
ports
are securely
mounted.
Attach a
tag
to
the
instrument,
giving your
home
address
and
the
trouble
with
the
unit.
Pack very
carefully
in
a
nigged
container, u»-
ing sufficient
packing
material (cotton,
shredded news-
paper, or
excelsior), to
make
the unit
completely immov-
able within
the container.
The
original
shipping carton
is
satisfactory,
providing the
original
inserts
are
used or
sufficient
packing
material inserted
to
keep
the instru-
ment immovable.
Ship
by
prepaid
Railway
Express,
if
possible, to Electronic
Instrument
Co.
,
Inc.
,
33-00 North-
ern Blvd.,
Long
Island
City
1,
New
York.
Return ship-
mentwill be
made by
express collect.
Note
that
a
carrier
cannot be held
liable for
damages
in
transit
if
packing
IN
HIS
OPINION,
is
insufficient.
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Table of Contents
Troubleshooting
