UT320 units shipped or retrofitted after 2005/07/20 are equipped with a master reset button on the back panel.

To perform a Master Reset on a UT320 instrument:

1. Turn OFF the instrument using the rear panel power switch

2. Locate the master reset button on the rear panel opposite the main power switch

3. Press and hold the reset button for at least 6 seconds.

4. Turn on the instrument's main power using the rear panel power switch

5. Press the power button on the front panel to restart the instrument

To perform a Master Reset on a UT340 instrument:

1. Turn off the instrument using the rear panel power switch. Wait at least 10 seconds.

2. While holding the ‘F1’ key on the front panel, turn on the rear panel power switch.

3. Continue holding the ‘F1’ key for approximately 3 seconds.

4. Release the ‘F1’ key and press the ‘6’ key on the numeric keypad.

5. After approximately 8 seconds, the instrument will beep twice and the display will come up in pulser mode with all variables set to their minimum values.

6. If the ‘F1’ key is not held for at least 2 seconds, the instrument will continue with a normal power-up sequence.

7. If the ‘6’ key is not pressed within 3.5 seconds after releasing F1, or if any other key is pressed, the instrument will continue with a normal power-up sequence.