Agilent Technologies 3200P, User Manual, Page: 53 / 116

Troubleshooting and Maintenance 3
3200P pH Meter User Guide 53
Check the potential (mV) value
Disconnect the pH electrode. Install the short circuit plug
(G4383- 40000, shipped with the meter) into the pH/pX
socket. Turn on the meter. Enter the pH measurement state.
At this moment, the meter should display a potential (mV)
reading between –0.5 to 0.5 mV (also called mV Zero). If yes,
this indicates that the meter is functioning properly. If the
potential (mV) reading significantly deviates from zero, then
use the Adjust mV Zero function to adjust mV Zero. See
“To
adjust mV zero” on page 33 for more information. After
adjustment, the potential (mV) reading should be near to
zero. If the potential value (mV) reading cannot be adjusted
near to zero by the mV Zero adjustment, this indicates a
problem with the meter. Contact Agilent service.
Check the pH value
Disconnect the ATC probe. Set up the meter as manual
temperature input. See
“To manually set the solution
temperature” on page 27. Set the solution temperature to
25 °C. When the potential (mV) is zero, the meter should
display a pH reading among 6.99 to 7.01 pH. If yes, this
indicates the electrode calibration data of the meter is
acceptable. If not, there may be a problem with the electrode
calibration data. Check the slope of electrode again. Press
[View] , select Last pH Calib and press [Enter] . Now, view the
calibration data and slope of last calibration. If the
calibration data is severely out of the expected range (the
meter displays an error message, see
Table 4 on page 57),
this indicates a problem in the last electrode calibration,
which may lead to a large measurement error. Recalibrate
the electrode. Pay attention to the Buffer Group selection
during calibration.
N O T E
In the measurement state, the meter may display an error message
simultaneously with measurement data.