Metex 2200P pH Analyzer/Controller - Manual (Page 26)

Model 2200P Page 24
7.3 Range Change
7.3.1 The following ranges are offered for the 2200P:
• 0 to 14 pH
• 2 to 12 pH
• 0 to 10 pH
• 4 to 10 pH
7.3.2 You may change the range of your instrument by making adjustments to the circuit
board on the swing-out panel. The analog output limits will change automatically
when you change the range. You may also wish to adjust the range expand at this
time. See Section 5.4. To change the range proceed as follows:
a) Enter the Utility menu as described in 7.2.1.
b) Press MENU until the CALIBRATION LED illuminates which is “Range Change”
in the Utility Menu. See table in 7.2.2.
c) Rinse the probe then place it in a 7 pH buffer. Adjust potentiometer R52 (zero)
[see diagram] to make the display read the value shown in the table below for
the range you have selected.
d) Rinse the probe and place it in either 4 pH buffer or 10 pH buffer. Adjust
potentiometer R53 (span) [see diagram] to make the display read the value
shown in the table below for the buffer and range you have selected.
e) Press RUN to return to on line or press MENU to proceed to another item in the
Utility Menu.
Display reading with probe in buffer:
Range 7 pH 4 pH 10 pH
0 to 14 pH 2.5 1.43 3.57
2 to 12 pH 2.5 1.0 4.0
0 to 10 pH 3.5 -- 5.0
4 to 10 pH 2.5 0.0 5.0
f) After returning to on-line, recalibrate as described in Section 5.2.