Eico ST 40 - Servicing

PAGE
11
the
lowest
AC
volts
range
of
yourVTVM
(also
improves
signal
to
hum from
generator).
Use a
high
input
imped-
ance VTVM for
all
AC
signal
voltage
measurements;
a
VTVM
or20,
OOQQ/v
VOM for
DC
volts
measurements.
If
the
trouble
is
an
excessively
distorted
output,
try
tube
replacement,
signal
tracing,
or
proceed
directly
to
volt-
age and
resistance
measurements.
When the
defective
stage
is
localized,
proceed
to a
resistance
and
voltage
check
of
the
stage,
using
the
data
in the
VOLTAGE
and
RESISTANCE
chart.
Dis-
connect
the
amplifier
from
the
power
line
and
discharge
capacitors
prior
to
making
any
resistance
check,
and
prior
to
removing
any
or all
of the
7591
output
tubes.
Do not
turn
the
amplifier
on
with
any
of
the
output
tubes
removed.
TRANSFORMER
TEMPERATURE
The
transformers
used
In this
unit
run at a
temperature
less
than
195°F despite
the fact
that
the
safety
limit
is
at a
much
higher
221°F.
Although
195°F
is cool
for
a
transformer,
it
is
very
hot to
the
touch.
Transformers
which seem
too
hot
when
touched
with the
hand,
are
usually
good
and
are
actually
not
overheating.
Output
transformers
usual
1
y
run cooler
than
power
trans-
formers.
Some
output
transformers
may
appear
hotter
than
others
due
to
being
located
near
hot
components
such
as
output
and
power
tubes
and
powertransformers.
SERVICE
If
trouble
develops
in
your
instrument
which
you
can
not
remedy
yourself,
write
to
our
service
department-
listing
all
possible
Indications
that
might
be
helpful.
List,
also,
any
code
numbers
in
red
under
the
words
INSTRUCTION
MANUAL
on
the
cover.
If
desired,
you
may
return
the
instrument
to
our
factory
where
it
will
be
placed
in
operating
condition
for
$13.50p!us
the
cost
of
parts
replaced
due
to
their
being
damaged
in
the
course
of
construction.
NOTE;
Before
return-
ing
this
unit,
be sure
all
parts
are
securely
mounted.
Attach
a tag
to the
instrument,
giving
your
home
ad-
dress
and
the
trouble
with
the
unit.
Pack
very
care-
fully
In a
rugged
container,
using
sufficient
packing
material
(cotton,
shredded
newspaper,
or
excelsior),
to
make
the
unit
completely
immovable
within
the
con-
tainer.
The
original
shipping
carton
is
satisfactory,
providing
the
original
inserts
are
used
or
sufficient
packing
material
inserted
to
keep
the
instrument
im-
movable.
Ship
byprepaldRailwayexpress,
ifpossible,
to
Electronic
Instrument
Co.,
Inc.,
33-00
Northern
Blvd.,
Long
Island
City
1,
NewYork,
Return
shipment
will
be
made
by
express
collect.
Note
that a
carrier
cannot
be
held
liable
for
damages
In transit
ifpackinq
IN
HIS
OPINION,
Is
insufficient.