3 Calibration Procedures
92 Keysight 34420A Service Guide
To Unsecure the Meter Without the Security Code
To unsecure the meter without the correct security code, follow the steps below. A
procedure to unsecure the meter is given on “To Unsecure the Meter for
Calibration” on page 70. Also see Chapter 5, "Electrostatic Discharge (ESD)
Precautions" before beginning this procedure.
1 Disconnect the power cord and all input connections (both front and rear
terminals).
2 Remove the instrument cover. Refer to the disassembly drawing on page 155.
3 Connect the power cord and turn on the meter. Be careful not to touch the
power line connections.
4 Apply a short between the two exposed metal pads on JM500 as shown in
Figure 3-1.
Figure 3-1 Applying short on JM500
Do not touch exposed mains.