Omron NT31 Operation Manuals page 11

Precautions
Do not attempt to take the unit apart and do not touch any inter-
nal parts while the power is being supplied. Doing either of
these may result in electrical shock.
Switch OFF the NT31/NT31C power before replacing the
backlight. Otherwise you could sustain an electric shock.
Do not touch the backlight immediately after switching OFF
the power supply.
Otherwise burn injuries may result due to the high tempera-
tures.
WARNING
WARNING
CAUTION
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