23
Calibration Procedure
The 4021 should be allowed to warm-up for a minimum of 5 minutes before beginning the
procedure. The adjustments are accessed by removing the four feet screws, then lifting off the top
cover only. The locations of the adjustments are shown on drawing number 4021-700 in Chapter
11.
Voltmeter Adjustment
1.
Select the 20
Ω
Range on the 4021.
2.
Connect the Voltage Calibrator to the Sense terminal observing polarity.
3.
Apply -100mV and adjust R40 for a display reading of “10.000” ± 1 digit.
4.
Apply -100µV and adjust R37 for a display reading of “0.010”.
5.
Repeat steps 3 and 4 until both are in specification.
6.
Disconnect the Voltage Calibrator.
Full Scale Adjustment
1.
Select the 20k
Ω
Range.
2.
Connect the Kelvin clips to a 10
Ω
standard resistor.
3.
Adjust R37 for a display reading of “0.010”.
4.
Connect the Kelvin clips to a 10k
Ω
standard resistor.
5.
Adjust R15 for a display reading equal to the resistor value.
6.
Check all remaining ranges with the appropriate standard resistors. All ranges must
be within the specifications outlined in Chapter 3.
Note: The 2M
Ω
range uses just 100
nano
-amps of test current to make the resistance
measurement. This amount of current can easily be disturbed by movement of people or
objects in the test area. When checking this range, keep movement to a minimum.
Note: When using the 2M
Ω
Range, allowe approximetly 30 seconds for the readings to
stabilize.
End of procedure.
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