Prokit's Industries MT-4017 - Manual (Page 9)

3. Unit key
1) Unit set
Press the key can change the parameter unit: lux, ftc.
2) Back light contrl
If press the key >2sec. the back light will be turned on,
Press the key once >2sec. the light will be turned off. If
the back light is not closed within 60 seconds, it will be
turned off automatically.
3) Auto power off set
When the meter is powered on, it is under auto
power off mode. The meter will power itself off after 20
minutes if no key operation.
Cancelled auto power off function: press Unit key
when power on until the LCD display AP OFF, then
press the ON/OFF key to confirm the setting. And then
the meter will be power off.
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