Technical data

Calibration Procedures 3
34980A Service Guide 61
Internal DMM Adjustments
You will need a test input fixture to adjust the internal DMM 
(see page 52).
Zero Adjustment
Each time you perform a zero adjustment, the Internal DMM stores a new
set of offset correction constants for every measurement function and
range. The Internal DMM will sequence through all required functions and
ranges automatically and store new zero offset calibration constants. All
offset corrections are determined automatically. You may not cor rect a
single range or function without re- entering ALL zero offset correction
constants automatically. This feature is intended to save calibration time
and improve zero calibration consistency.
Zero Adjustment Procedure
The zero adjustment procedure takes about 5 minutes to complete. Be sure
to allow the instrument to warm up for 2 hours before performing the
adjustments.
Follow the steps outlined below. Review “DMM Test Considerations" on
page 53 before beginning this test.
1 This procedure will use the copper shorts installed on input test
connector. Leave the Current input connection open.
2 Set the DC VOLTS function.
3 Send the value 0.000000 to the instrument using the
CALibration:VALue 0.000000 command.
4 Calibrate the instrument using the CALibration? command.
5 Perform the “Zero Offset Verification" on page 53 to check zero
calibration results.
NOTE
Never turn off the Internal DMM during Zero Adjustment. This may
cause ALL calibration memory to be lost.