Dc Voltage Function Offset Test - Agilent Technologies 3458A Calibration Manual

DC Voltage Function
Offset Test
Turnover Check
Chapter 3 "Adjustment Procedures" to make adjustments.
This procedure tests the DCV offset voltage specification on the 10V range.
This reading and the 10V and -10V readings from the previous DCV gain
test are used to do a turnover check of the A-D converter and verify its
linearity.
1. Connect a low thermal short across the front panel HI and LO input
terminals of the DMM under test (see Figure 1).
2. Set the range of the 3458A under test to 10V
3. Let the instrument sit for five minutes before taking a reading to allow
the short and relays to thermally stabilize.
4. Execute Trig and record the offset reading on the Test Card.
The turnover check is a calculation using the unit under test readings from
tests 4, 5, and 6 on the Test Card. This check verifies the linearity of the
A-to-D converter which is fundamental to the 3458A's calibration technique.
Calculate the following:
(UUT Reading #4) - (UUT Reading #6) = A
(UUT Reading #5) - (UUT Reading #6) = B
If the A-to-D converter is linear. the difference in the absolute values of
A and B will be less than or equal to 4 µV.
Chapter 2 Operational Verification Tests 17