HP 740B Operating And Service Manual page 46

Model 740B
Section V
Table 5-4. 6.VM and VM Accuracy Test Data, 1 V - 1000 V
DIVIDER CONNECTIONS,
IN-TOLERANCE 740B INDICATIONS
740B INPUT AND
POWER SUPPLY OUTPUT
6.VM MODE
VM MODE
A and B 1 V ±O. 000055 V
1 V ±0.02 V
A and C 2 V ± 0.00014 V 2 V ± 0.2 V
A and D 3 V ± O. 00019 V
3 V ± 0.2 V
A and E 4 V ± 0.00024 V 4 V ± 0.2 V
A and F 5 V ± 0.00029 V
5 V ± 0.2 V
A and G
6 V ± 0.00034 V 6 V ± 0.2 V
A and H 7 V ± O. 00039 V
7 V ± 0.2 V
A and I 8 V ± 0.00044 V
8 V ± 0.2 V
A and
J 9 V ± O. 00049 V 9 V ± 0.2 V
A and K 10 V ± 0.00054 V 10 V ± 0.2 V
A and L 100 V ± 0.0054 V
100 V ± 2V
A andM
1000 V ±
0.054 V
1000 V ± 20 V
- - - - - NOTE - - - - - -
p. Set 740B controls as follows:
q. Adjust ZERO control for a zero indication on
the 740B meter.
1. Make minor changes in the power
supply output at each point to main-
tain null on the null detector.
2. Periodically check null detector zero.
3. Zero the 740B input whenever
changing ranges.
o. Reconnect the test setup as shown in Figure
5-9. Do not connect the reference supply and
power supply + leads yet.
It is not necessary to short the +
and - leads when adjusting ZERO
control due to the low impedance
(1 kQ) across the input terminals.
r. Connect the 1 V reference supply and stable
power supply + leads to point K on the divider.
Adjust the power supply output for null on the
null detector.
s. Measure the voltage (at point B)with the 740B
(6.VM mode). Compare the reading with the
tolerances listed in Table 5-5.
t. Switch FUNCTION to VM; depress Xl SENSI-
TIVITY. Compare the 740B meter reading
with the tolerances listed in Table 5-5.
u. Move the 1 V reference supply and power
supply + leads to point L and then to point M
on the divider, measuring the voltages each
time at point B in both 6.VM and VM modes.
Compare the indications with the tolerances
given in Table 5-5.
- - - - - N O T E - - - - - -
1. Zero the 740B input each time
RANGE is changed. The ZERO
control is more sensitive on the
lower ranges. Depress
X10 3
SENSITIVITY to zero the input
on the 1 mV range.
2. Periodically check null detector
for null and adjust (if necessary)
the stable power supply output to
mainta in null.
- - - - - - N O T E - - - - -
· . 6.VM
· 100 mV
· 00.000
· . X104
FUNCTION . . .
RANGE . . • . .
VOLTAGE SET.
SENSITIVITY. .
1. Set power supply output to 2 V. Make minor
changes in the output voltage, if needed, to
maintain a null indication on the null detector
(10 JlV
range).
m. Measure the voltage in 6.VM and VMmodes.
Indicated voltage should be within the tolerances
listed in Table 5-4.
n. Progressively move up the divider, applying
the voltage shown at each point and measuring
the voltage at that point in 6.VM and VM modes
with the 740B. Compare the voltage readings
with the tolerances listed in Table 5-4.
Table 5-5. 6.VM and VM Accuracy Test Data, 1 mV - 100 mV
1 V REFERENCE SUPPLY
IN-TOLERANCE
AND STABLE POWER
VOLTAGE AT 740B INDICATIONS
SUPPLY + LEADS
POINT B
6.VM VM
Point K 100 mV 100 ±O. 0064 mV 100 mV ±2 mV
Point L 10 mV
10 ±O. 0015 mV
10mV±.2mV
Point M 1 mV
1 ± 0.001 mV 1 mV ±. 02 mV
01794-1 5-9