You can switch off the backlight (illumination) of the LCD screen of the E5071C. This extends the life of the backlight when using it continuously over a long period.
Press System key.
Press Backlight to switch the backlight on/off.
Switching off the backlight causes indications on the LCD screen to be almost invisible.
The backlight that has been switched off can be turned on again by pressing any key from the front panel.