Programming instructions

Chapter 2 Operational Verification Tests 17
Chapter 3 "Adjustment Procedures" to make adjustments.
DC Voltage Function
Offset Test
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 on page 23).
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.
Turnover Check 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.