4-Wire Ohms Function; 44491A Offset Test - HP 3457A Service Manual

Operational Verification Tests
Rear Input Operational Verification Tests
(44491A General Purpose Relay Assy)
4-100. DC Voltage Function
-
44491A Offset Test
4-101. Equipment Required. Low thermal (copper) shorting wires are required f o r this procedure.
1. Set the I-IP 3457A t o the D C Voltage function (DCV) and the number of digits displayed (DIGITS
DISP) t o six.
2. Close channel 0. (Press the CHAN configuration key, enter the number 0 and press the ENT key).
3. Test the HP 3457A input offset o n the 30 V, 3 V and 300 mV ranges and record the reading of
each range o n the Test Record provided a t the end of this section. Begin with the 30 V range t o allow
any therrnal voltages which might affect the readings o n
I
he lower ranges t o dissipate.
4. If any of the offset readings a r e beyond the limits specified in Table 4-33 and o n t h e Test Record,
the instrument should be calibrated o r repaired. Refer t o Section V f o r calibration procedures.
3457A
I
nput
S h o r t
Short
S h o r t
t
3457A
Range
Table 4-33. DC Voltage Offset Test Limits (44491A)
4-102. 2-Wire Ohms Function
-
44491A Offset Test Limits
3 0 V
3 V
3 0 0 m V
4-1 03. Equipment Required. Low therrnal (copper) shorting wires are required f o r this procedure.
3457A
Set
Up
1. Set the H P 3457A t o the 2-Wire Ohms Function,
3
K o h m range. Set the offset compensation
(OFFSET COMP) on, and the number of digits displayed (DIGITS DISP) t o six.
T e s t L i m i t s
H i g h
I
Low
DCV
DCV
DCV
2. Close channel 0. (Press the CHAN configuration key, enter the number 0 and press the ENT key).
3. Use the Test Record t o record the offset reading f o r the 3 Kohm range.
+
00.00020 V
+
0.000010 V
+000.0070 m V
4. Test the ohms offset o n channels 0 through
7
with the instrument set t o the 3 K o h m range. Record
t h e reading of each channel on the Test Record provided at the end of this section.
-
00.00020 V
-
0 . 0 0 0 0 1 0 V
- 0 0 0 . 0 0 7 0 m V
5. If any of the offset readings are beyond
f
0.002207 KOhms, the instrument should be calibrated o r
repaired. Refer t o Section V f o r calibration procedures.
4-104. 4-Wire Ohms Function
-
44491A Offset Test Limits
4-105. Equipment Required. Low thermal (copper) shorting wires are required f o r this procedure.
I. Set the H P 3457A t o t h e 4-Wire Ohms Function (OHMF). Set the offset compensation (OFFSET
COMP) on, and the number of digits displayed (DIGITS DISP) t o six.