Null Detector; Versus Range Checks - Fluke 893A Instruction Manual

n.
Connect
the output
of the dc voltage calibrator
between
the
LO
and HI
INPUT
terminals.
o.
Apply
the dc input
voltages versus
the
ranges
in-
dicated
in
Figure
4-5,
observing
that the
meter
indicates full-scale
(+1)
±
1 -
1/2
small
divisions.
4-30.
When
the
results
of the
checks agree
with
the
information
given, the Null Detector and Divider
cir-
cuitry are
functioning
properly and
the test
equipment
can
be disconnected from
the instrument.
INPUT DC VOLTAGE
RANGE NULL
SENS
.001
1 1
mv
.01
1
.
Olv
.
1
1
.
1
v
1.0
1
TVM
10.0
10
TVM
100.0
100
TVM
1000.0
1000
TVM
Figure 4-5.
INPUT DC VOLTAGE
VERSUS RANGE-CHECKS
4-31.
KELVIN-
VARLEY
DIVIDER CHECKS
4-32.
The
Kelvin- Varley Divider Checks require
the
use
of
a dc
voltage calibrator.
The
Precalibration and
Troubleshooting
Checks
of
paragraphs 4-21
through
4-30
must
also have been performed
to
ascertain
that
the associated Instrument
circuitry
is
functioning
correctly.
To perform
the
checks, apply ac power
to the instrument and proceed
as
follows:
a.
Place
the
Model
893 controls as follows:
POWER
RANGE
NULL
SENS
MODE
Readout
dials
ON/LTNE
OPR
10
.001
+
10. 000
-
A4TP11
FULL-SCALE INPUT
Ft"".
;
5 u
SATURATION
CONDITION
4
1
:ffz
5
u
—j
C
-
—
c
T...
u
A4TP13
A4TP15
Note:
HORIZONTAL
SWEEP
-
5
MSEC/CM
Figure
4-6.
NULL DETECTOR
WAVEFORMS
4-10
b.
Apply
+10
volts dc from
a dc voltage calibrator
between
the
Model
893
LO
and HI
INPUT
terminals.
c.
Adjust A2R33
for a
zero-center
meter
indication
on
the Model
893
d.
Apply
the dc
input voltages versus
the Readout
dial settings
of
Figure
4-7,
observing
that
the
Model
893
meter
indicates
zero-center
within the
major
division deviation.
INPUT
DC
VOLTAGE
READOUT
DIAL SETTINGS
MAJOR
DIVISION
DEVIATION
11.000
10.
99
X
±5.5
10.
000
10.00
0
null reference
10.
00
9-99
X
±5. 0
9.999
9.
99 90
±4. 99
8.
888
8.
88 80
±4, 44
7.777
'^77 20
±3. 88
6.666
6.66
^
±3.33
5.555
5.55
5(}
±2.77
4.444
4.44 40
±2.
22
3,333
3-33 30
±1, 66
2.222
2,22 20
±1.
n
1.111
1.
11 10
± .55
1.000
1.00
Q
± .5
Figure 4-7. INPUT VOLTAGES
VERSUS READOUT
SETTINGS
-
CHECKS
4-33.
When
the results
of
these checks agree
with the
information
given, the Kelvin- Varley
Divider
circuitry
is
functioning properly and
the test equipment
can be
disconnected from
the instrument.
4-34.
RECORDER OUTPUT
OPTION CHECKS
4-35.
The Recorder
Output Option Checks
require
the use
of
a dc
differential voltmeter.
Circuit
wave-
forms
are
illustrated
in
Figure 4-8,
To perform
the
checks, apply ac
power
to
the instrument and proceed
as
follows;
a.
Connect
the inputs
of a dc differential voltmeter
to
the
rear panel HI and
LO RECORDER OUTPUT
terminals and
rotate the associated
level control
fully
clockwise.
b.
Connect
a shorting jumper between
the
LO
and HI
INPUT
terminals
of the
Model
893
and
place the
controls as follows:
POWER
RANGE
NULL
SENS
MODE
Readout
dials
ON/LINE
OPR
1
.001
+
.00100
c.
A
dc voltage
of -0. 2 to -0. 28
volts dc should be
indicated on the dc
differential
voltmeter connected
to the
RECORDER OUTPUT
terminals.
893A