General Tools and Instruments CMM880 - Manual (Page 9)

Automatic Calibration :
Turn off the meter , then plug the meter
probe into the 33% salt bottle and then
power on the meter by pressing " ON
/OFF button and the C/F button at the
same time. When LCD screen shows
a full display, release the ON/OFF key.
You will see the display of C and F
at the lower right corner of LCD screen
, then release the C/F button. The LCD
will display only the default setting
of temperature unit C or F. Press
"RST" key and you will see a "% MIN"
display on the right upper corner. (See
Fig.H) ,please leave the meter in the
bottle for at least 40 minutes and the
meter will start the calibration process
automatically. When the calibration for
33% is done ,you will see a MIN and
MAX display on the LCD screen.
You may turn off the meter to finish 33%
low humidity calibration or keep going
for 75% high humidity calibration.
Remove the meter probe from the 33%
salt bottle and plug it into the 75% salt
bottle.
Then press "MN/MX" button, you will
see a " % MAX" display on the LCD.
(See Fig.I)Then leave the meter in the
75% bottle for next 40 minutes.
When the 75% calibration is completed,
the screen shows MIN and MAX ,(See
Fig.J) ,it means the 75% calibration is
completed , and the meter resume to
the normal measuring mode.
You can remove the meter from the
75% bottle now .
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