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DATA PRECISION 938 User Manual

DATA PRECISION 938
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42-5124
MODEL
938
4.6
POWERSUPPLY
a.
Power
for
the
Model
938
is
derived
from
either
a
9-volt
tran
sistor
radio
type
battery
or
from
a
Battery
Eliminator
(BE9).
When
a
battery
eliminator
is
used,
the
internal
battery
is
discon
nected
from
the
circuit.
b.
A
low
battery
sense
circuit
in
the
Model
938
continuously
com
pares
a
fraction
of
the
battery
voltage
(or
BE9
output)
against
a
5.8V
reference
and
generates
the
“
LO
BAT
”
drive
signal
when
the
input
is
approximately
7
volts.
Figure
4-9
illustrates
the
generation
of
excitation
sup
plies
and
voltage
levels
in
the
model
938.
Figure
4-9
•
Model
938
Power
Sourcing
Schematic
4-12
MODEL
938
MAINTENANCE
Chapters
MAINTENANCE
5.1
GENERAL
CAUTION
Model
938
is
covered
by
a
one-year
warranty,
and
it
should
be
returned
to
the
factory
for
maintenance
within
the
warranty
period.
At
tempts
to
make
any
extensive
repairs
within
the
warranty
period
may
invalidate
the
warranty.
If
repairs
are
needed
after
the
warrany
period,
only
qualified
technicians
should
attempt
to
effect
such
repairs
and
should
use
test
instruments
and
standards
calibrated
within
the
accuracy
and
tolerances
of
the
instrument
specifications.
Note
that
the
warranty
does
not
cover
damage
caused
by
leaky
batteries.
Model
938
has
been
designed
with
a
minimum
number
of
com
ponents,
and
is
intended
to
deliver
years
of
reliable
service.
In
addition,
all
components
have
been
screened
and
tested,
prior
to
use,
in
an
extensive
quality
control
procedure,
and
the
final
assembly
has
been
burned
in
prior
to
final
test
and
shipment.
5.2
TROUBLE
SHOOTING
STRATEGY
Should
the
meter
performance
indicate
the
need
for
repair,
a
well-defined
strategy
should
be
used
to
isolate
the
cause
of
malfunction.
Such
a
strategy
begins
with
an
analysis
of
the
symptoms
of
malfunction
in
order
to
keep
to
a
minimum
the
repair
and
replacement
operations
within
the
meter
assembly.
Much
can
be
learned
from
an
analysis
of
the
meter
performance
under
varying
input
conditions.
Figure
5-1
illustrates
the
type
of
5-1

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DATA PRECISION 938 Specifications

General IconGeneral
BrandDATA PRECISION
Model938
CategoryMeasuring Instruments
LanguageEnglish