16 17
ing message “time-out”, then shows “WRONG” and it is not
possible to complete calibration.
• At the end of calibration, with the meter set as pH control-
ler, the instrument checks if the offset is between -30 and
30 mV and the slope between 53.5 and 62 mV/pH. If the
values are not within these ranges, the message “OLd
ProbE” scrolls twice across the LCD. The electrode is still
working, but it is necessary to perform a cleaning proce-
dure (see “Electrode conditioning and maintenance” and
“In-line Cleaning” sections) or replace it.
If the offset is outside the -60 to 60 mV range, the “dEAd
ProbE” message will scroll across the LCD and the corre-
sponding error is activated. The electrode has to be replaced
as soon as possible because there is no reliability on the
measured pH values.
One-point calibration with manual selection of the calibration value.
A one-point calibration at a value different from the standard
buffer values is possible by entering the desired calibration
value. This is the actual pH value at the current calibration
temperature.
• Enter the pH calibration mode (no matter if
the standard or NIST buffer set is selected),
then press (ALT+) SETUP while the second-
ary LCD is displaying the first buffer value
(pH 7.01 or pH 6.86).
• The pH calibration value will switch
to 7.00, the first digit starts blinking
and it is possible to change its value
simply using the æ or key.
• Once selected the first digit value, press the key: the first
digit will be fixed and the second one will start blinking.
Pressing of the key repeatedly will result on circularly
moving on the secondary LCD.
• When the desired calibration value is reached (must be
within 0.00 to 16.00 pH), press the CFM key to confirm
and the calibration will proceed as described above.
• If the selected value is outside boundaries, the confirma-
tion is not accepted and the first digit keeps blinking (waiting
for confirmation of a valid value).
Note The electrode should be submerged ap-
proximately 4 cm (1
1
/
2
’’) in the solu-
tion. The temperature probe has to be
located as close as possible to the pH
electrode.
Note When it is not possible to immerse the Potential Matching Pin
together with the pH electrode in the solution, disable the
differential input by setting setup item I.04 to “OFF”.
• When the reading becomes stable,
the probe indicator will stop flash-
ing (after about 30 seconds), and if
the pH value is close to the selected
buffer, the “CFM” indicator will start
blinking, otherwise the “WRONG”
indicator, the pot and the BUF tags
will start blinking.
• Press the CFM key to confirm calibration. The meter will
show the scrolling message “Press CFM again to confirm
the current buffer or right to escape” (to prevent from con-
firming the calibration point inadvertently).
Pressing again CFM, the secondary LCD will display the
second expected buffer value.
• In the second case (pH value not close to the buffer) the
meter will remain in the same state until the reading be-
comes unstable or the calibration mode is quitted.
• For the second buffer value it is possible to choose be-
tween pH 4.01 and pH 10.01 (or pH 4.01 and pH 9.18 if
the NIST set has been selected). Use the æ or key to
switch between the two possibilities.
• Once selected the buffer, the procedure is the same as for
the first calibration point.
Note A time-out of 2.5 minutes is present for the pH electrode
response time. During calibration, if the pH reading is not
stable after 2.5 minutes, the device displays twice the scroll-
