Fluke 732a - Acceptance Test; Calibration Procedures; Null Verification

732A
2.
Set the
BATTERY
OPR
switch to
ON
and
remove
ac
line
power
from
the
instrument.
3.
Remove
the
AC
Module.
4.
Locate
the
voltage
selector
switches
(slide
switches,
top
of PCB,
near rear
panel). Set the
switches
so that
the
dots on
the switch
actuators
select
the
correct
line
voltage.
As
shown
in Figure
4-5.
5.
Reinsert
the
AC
Module,
replace
the
screws.
6.
On
the rear
panel,
change
the
mark
to the
appropriate
box,
under
the
SUPPLY/SETTING
heading,
to
indicate
the
present
power
configuration.
7.
Replace
the
line
fuse
with
one
of
appropriate
value.
8.
After
verifying
that
the local
ac
line
voltage
matches
the
voltage
selected
on
the
732A, apply
ac
line
power to
the
instrument.
4-30.
ACCEPTANCE
TEST
4-31. Use
the
following
procedure
to
verify
that the
instrument
is
operational.
The
required test
equipment
is
listed
in
Table
4-1.
Equivalent
instruments
may be
used,
provided
the
minimum
specification
is met.
1.
Check
the
IN
CAL
indicator
on
the front
panel.
If
illuminated,
proceed
to
step 2. If
not,
complete
steps
a
through
f.
a.
If
the
IN
CAL
indicator
was
not lit,
set the
rear
panel
BATTERY
PWR
switch
to
OFF
and
apply
ac
power
to
the
instrument
using
the
Variac,
to
the
Supply
Setting
limit
listed
on
the
rear
panel.
b.
Adjust
the
Variac
for 1
20V
ac
output.
The
ac
line
current
should
be
less
than
0.3A.
c.
Set
the
BATTERY
PWR
switch
to
ON.
The
ac
line
current
should
be
less
than
0.35A if the
battery
is
dead
(BTR
Y
CHG
indicator
blinking).
If
BTRY
CHG
indicator
is
on
steadily,
the
ac line
current
should
be
less
than
0.35A.
d.
Allow
the
732A
to
stabilize
(under
power)
for
24
hours.
e.
If a
standards
laboratory
is
available,
perform
the
External
Calibration
Procedure
described
in
Section
4,
If a
standards
laboratory
is
not
available,
send
the
732A
to
a
Fluke
Technical
Service
Center
or
an
independent
standards
laboratory
for
calibration.
f.
Once
the 732A
has
been
calibrated,
proceed
to
step
2.
2.
Apply
ac
power
of
the correct
voltage and
frequency
to the
instrument.
The
AC
PWR
and
BTRY
CHG
indicators
should
both
be
on.
3.
Measure
the
value
of the
Oven
Temperature
Thermistor
at
the
front
pane!
binding
posts
with
Multimeter
A.
The value
should
be
within
±1 ohm
of
the
value
shipped
with
the
instrument.
4.
Check
the
output
voltage
at
the
lOV
output
using
Multimeter
A. It
should
be
accurate
within
the
performance
limitations
of
the
Multimeter.
5.
Measure
the
change
in
output
voltage
under
load.
To
make
this
measurement
correctly,
wire
Multimeter
A
to
the lOV and
lOV LO
binding
posts
(do
not
use
plugs)
and
measure
the
voltage.
Then
plug
the
1000
ohm
load
into
the same
binding
posts
and
measure
the voltage.
The
voltage
change
should
be
less
than 50
uV
or
5.0
ppm.
6.
Repeat
step
4
for the
IV and
I.OISV
outputs.
7.
If a
standards
laboratory
is
available,
verify
stability
by
comparison
to
standard
cells
or
another
pre-certified
732A.
This
step
is
optional.
8.
The
instrument
is
operational.
4-32.
CALIBRATION
4-33.
Complete
either
of
the
following
calibration
procedures
to
certify
the
732A.
Procedure
A
uses
direct
comparison
between
the
Unit
Under
Test
(UUT)
and
a
Certified
732A
to
calibrate
the
lOV
output.
The
lOV
output
of
the
UUT
is
then
transferred
to
a stable
adjustable
voltage
source.
The
voltage
source is
then
divided
down,
as
required,
for
comparison
with the
UUT
1
.0
1 8
V
and
1
V
outputs.
Procedure
B
transfers
the
voltage
from
a
bank
of
standard
cells to a
stable
adjustable
voltage
source,
then
divides
the
voltage
source
down,
as
required,
for
comparison
with
the
UUT.
4-34.
Either
procedure
may
be
used,
taking
into
account
the
available
test
equipment
and
the
degree
of accuracy
needed.
The
necessary
equipment
for
each
procedure
is
listed
in
Table
4-1.
4-35.
Null
Verification
4-36. Use
the
following
procedure
to
verify
the
accuracy
of
null
in
the
calibration
procedures.
The Null
Verification
procedure
identifies
the
thermal
voltages
present
and
allows
the
null
adjustment to be made
independently
of
them.
Use
the
Null
Verification
procedure
in
the
two
calibration
procedures (Procedures
A
and
B)
when
instructed
to
“verify
the null".
4-8