Performance Tests and Calibration 6
U1253B User’s and Service Guide 151
Calibration Security
A calibration security code is in place to prevent accidental
or unauthorized adjustments to the U1253B true RMS OLED
multimeter. When you first receive your instrument, it is
secured. Before you can adjust the instrument, you must
“unsecure” it by entering the correct security code (see
“Unsecuring the instrument for calibration” on page 151).
The security code is set as 1234 when the instrument is
shipped from the factory. The security code is stored in
nonvolatile memory, which does not change even when the
power is off.
Unsecuring the instrument for calibration
Before you can adjust the instrument, you must unsecure it
by entering the correct security code, either from the front
panel, or through PC remote interface.
The default security code is 1234.
From front panel
1 Turn the rotary switch to the position (you may
also start with another rotary switch position; but here
we assume that you will follow the exact steps listed in
Table 6- 2).
2 Press and simultaneously to enter the
Calibration Security Code entry mode.
You can unsecure the instrument and then change the security code from
the front panel or through the remote interface.
See “Resetting the security code to factory default” on page 156 if you
forget your security code.