Keysight E3631A, Service Manual

Page: 79 / 131

Calibration Procedures 3
Keysight E3631A Service Guide 77
The power supply is unsecured when you press the “Secure” key. You will see
the above message from the front panel for one second. The "CAL MODE"
message is displayed on the front panel after above message.
5 Turn off the calibration mode.
Turn off the power supply to exit the calibration mode.
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. See Electrostatic Discharge (ESD)
Precautions , in chapter 5 before beginning this procedure.
1 Disconnect the power cord and all load connections from front terminals.
2 Remove the instrument cover.
3 Connect the power cord and turn on the calibration mode by pressing the
"Calibrate" key while simultaneously turning on the power supply then
continue to hold the "Calibrate" key for about 5 seconds until a beep is heard.
Be careful not to touch the power line connections.
4 Apply a short between the two exposed metal pads on JP1
[1]
(located near the
main controller U17 on the top board). The exposed metal pads are outlined
with a small rectangular silkscreen. (See the component locator drawing for
the E3631-60002 top PC board in Chapter 6)
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 JP1
[2]
. (An error occurs if not removed.)
7 7 Turn off and reassemble the power supply.
Now you can enter a new security code. Be sure you take note of the new
security code.
NOTE
To re-secure the power supply (following calibration), perform this procedure
again.