Technical data

8 Service and Maintenance
Calibration Reference
206 E364xA User’s and Service Guide
To unsecure the power supply without the security code
To unsecure the power supply without the correct security
code (when you forget the security code), follow the steps
below. Refer to “Electrostatic Discharge (ESD)
Precautions” on page 174 before beginning this procedure.
1 Disconnect the power cord and all load connections from
the power supply.
2 Remove the instrument cover. Refer to the disassembly
drawing in
“General Disassembly” on page 179.
3 Connect the power cord and turn on the calibration mode
by holding down the Calibrate key as you turn on the
power supply and hold down the key until you hear a
long beep. Be careful not to touch the power line
connections.
4 Apply a short between the two exposed metal pads on
JP107
[1]
(located near U121). Refer to “Component locator
diagram for the main board assembly — top” on page 215
and “Component locator diagram for the main board
assembly — bottom” on page 216.
5 While maintaining the short, move to the security code
and enter any unsecure code in the calibration mode. The
power supply is now unsecured.
6 Remove the short at JP107
[1]
. (An error occurs if not
removed.)
7 Turn off and reassemble the power supply.
[1] For serial MY53xx6xxx, apply the short at JP12 (located near U10). Refer to
“Component locator diagram for the main board assembly — top (serial
MY53xx6xxx)” on page 218 and “Component locator diagram for the main board
assembly — bottom (serial MY53xx6xxx)” on page 219.
NOTE
Now you can enter a new security code. Ensure that you take note of the
new security code.