3 Calibration Procedures
50 Keysight 34980A Service Guide
Internal DMM Adjustments
You will need a test input fixture to adjust the internal DMM (see page 40).
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 correct 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 42
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 43 to check zero calibration
results.
Never turn off the Internal DMM during Zero Adjustment. This may cause ALL
calibration memory to be lost.