YSI pH1200 - Manual (Page 5)

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Clear (not active in mV mode)
Used to clear the unit when an error signal
appears. It clears all calibration values stored in
the internal memory. Under normal use, the key
will not be activated unless pressed and held for
2 seconds to prevent accidentally erasing stored
memory.
When the “Clear” key is pressed, all segments
of the LCD will be on. After about 2 seconds the
unit will enter the pH-AUTO mode. The “AUTO”
and “CAL” will be on and one of the buffers in the
pre-selected buffer set will start to flash. The unit
must be calibrated again before use.
Up/Down
The two keys are used to manually enter the
temperature values. They have no effect on the
unit when operating in ATC mode.
Stand/Slope
The “Stand” and “Slope” keys are used for pH
calibration of the unit. Pressing and holding
the Stand key while turning on the power, will
change the buffer set.
Meas. / Effic.
This key is used to bring the unit out of the AUTO
condition when operating in the pH-AUTOLOCK
or mV-AUTOLOCK mode.
Press and hold this key for 3 seconds, the LCD
will display the efficiency of the electrode.
B U F F E R S E T S E L E C T I O N
The pH1200 has two buffer sets: 7.00, 4.01, 10.01 and 6.86, 4.00, 9.18.
The meter is factory pre-set to 7.00, 4.01 and 10.01. To change the
buffer set, turn off the unit, then press and hold the “Stand” key while
turning on the unit again.
Note: There is no need to repeat this procedure every time the unit is
powered up unless the buffer settings need changed.
p H C A L I B R A T I O N
The pH1200 can perform a one, two or three point calibration.
Note: If the unit uses two or three point calibration, the first point must
be 6.86/7.00. The second point can either be 4.00/4.01 or 9.18/ 10.01.
CALIBRATION WITH AN ATC/TEMP PROBE
IN THE PH-AUTOLOCK MODE
1. Turn the unit on. Press “Clear” key for 2 seconds, all LCD elements
will light up. The meter clears all calibration values stored in internal
memory.
2. Connect the pH electrode to the BNC connector and the ATC/Temp
probe to the ATC/Temp connector of the unit: “ATC” will light up.
“pH” and “AUTO” will light up. One of the buffers in the buffer set
will flash.
3. Rinse the pH and ATC/Temp probes in distilled water and immerse
them in the first buffer solution (6.86/7.00 if doing a multipoint
calibration). Allow temperature reading to stabilize, then press and
hold “Stand” key for 2 seconds to calibrate. The “WAIT” icon will
flash until the unit detects a stable reading. Once the unit calibrates
the first point, the selected buffer remains lit up while the remaining
two buffers flash. The unit is ready to be sloped at the second buffer.
Note: If the first buffer solution is 6.86/7.00, at this moment,
press the “Mode” key. The instrument will save the calibration and
exit the calibration mode. Single point calibration is complete. If
the first buffer solution is 4.00/4.01, 9.18/10.00, at this moment,
the instrument will save the calibration and automatically exit the
calibration mode. Single point calibration is complete.
4. Rinse the pH and ATC/Temp probe in distilled water and immerse
them in the second buffer solution (either 4.00/4.01 or 9.18/10.01).
Allow temperature reading to stabilize, then press “Slope” key to
calibrate. The “WAIT” icon will flash until the unit detects a stable
reading. Once the unit calibrates the second point, the selected two
buffers light up and the remaining buffer starts to flash. The unit is
ready to be sloped at the third buffer.
Note: At this moment, press the “Mode” key and the instrument will
save the calibration and exit the calibration mode. 2-point calibration
is complete.