Calibration Procedures 1Keysight U1281A/U1282A Service Guide 43To reset the calibration security code to its factory defaultIf you have forgotten the correct calibration security code, you may follow thesteps below to reset the calibration security code to the factory default code.1 Note down the last four digits of the multimeter’s serial number (located at thebottom of the rear panel) before you begin.2 Press and together for more than 1 second during normaloperation mode to enter unsecured mode. and will be shown onthe secondary and primary display.3 Press for more than 1 second to enter the Default Security Code (DSC)mode. and will be shown on the secondary and primary display.4 Enter the last four digits of the multimeter’s serial number.– Press or on to move the cursor to the left or to the right.– Press or to increment or decrement the digit.5 Press to confirm your entry.– If the four digits entered are correct, the display will show . Thecalibration security code is now set to its factory default code, .– If the incorrect security code is entered, an error code will appear briefly,after which the multimeter will prompt you for the security code again.– To enter a new security code, see “To change the calibration security code”on page 41. Ensure that you record down the new security code.NOTE If you do not have a record (or have lost the record) of the security code, first trythe factory default code, .Hz Save Esc ShiftEsc ShiftHoldVsenseHz Save