HP 3457A Service Manual page 92

Rear Input Operational Verification Tests
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(44492A 10 Channel Multiplex Assy)
4-108. Preliminary Steps
1, Connect a shorting wire to the channel 0 inputs of the Terminal Block assembly as shown in
Figure 4-22.
2. Select the Scanner Input. (Press the TERM configuration key, enter the number 2 and press the ENT
key).
NOTE
The 44492A Multiplexer Assembly and the 3457A Multimeter must have been
calibrated as a unit for these tests to apply. Calibration procedures are provided in
Section V of this manual.
4-109. DC Voltage Function - 44492A Offset Test
4-110. Equipment Required. A low thermal (copper) shorting wire is required for this procedure.
3. Test the HP 3457A input offset on the 300 mV range and record the reading on the Test Record
provided at the end of this section.
4, If the offset reading is beyond + 000.0070 mV, the instrument should be calibrated or repaired.
Refer to Section V for calibration procedures.
4-111. 2-Wire Ohms Function - 44492A Offset Test Limits
4-112, Equipment Required. A low thermal (copper) shorting wire is required for this procedure.
1. Set the HP 3457A to the 2-Wire Ohms Function, 3 Kohm range. Set the offset compensation
(OFFSET COMP) on, and the number of digits displayed (DIGITS DISP) to six.
2. Close channel 0. (Press the CHAN configuration key, enter the number 0 and press the ENT key).
3, Use the Test Record to record the offset reading for the 3 Kohm range.
4. Test the ohms offset on channels 0 through 9 with the instrument set to the 3 Kohm range. Record
the reading of each channel on the Test Record provided at the end of this section.
5. If any of the offset readings are beyond + 0,004210 KOhm, the instrument should be calibrated or
repaired. Refer to Section V for calibration procedures.