Omron NT31 Operation Manuals page 224

System Maintenance
Backlight Brightness Adjustment
The NT31/NT31C allows the brightness of the backlight to be adjusted in 3 steps.
The "BRIGHTNESS ADJUST" screen enables you to make the adjustment while
actually checking the brightness on the screen. The length of hours the backlight
lasts in a normal temperature are as follows.
High contrast:
Low, middle contrast: 25000 hours
Adjust the backlight brightness by following the menu operation from the System
Menu shown below.
Select "Contrast Adjust".
Adjust the contrast with the touch switches in
the left half of the screen.
[ ]: Increase 10 steps
[Y]: Increase 1 step
[B]: Decrease 1 step
[ ]: Decrease 10 steps
Press "Quit".
The contrast is set and the NT31/NT31C re-
turns to the "I/O SETTINGS MENU" screen.
10000 hours
Select "Maintenance Mode".
Section 6-11
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