1. Warning tone sounds when the “Measure” button is pressed
This indicates that the circuit is open and current is unable to flow. Causes may include
the following:
a.
The “measure” button was pressed while the electrode was not immersed in
solution.
b.
If the warning tone sounds with the electrode immersed in solution and the meter
display off-scale, then the current electrode circuit is broken and the electrode
needs to be replaced.
c.
If the electrode is in solution and the warning tone sounds discontinuously, a
reading may be displayed, but it is likely not very stable. This indicates that
there could be a large offset potential between the two current electrodes that
cannot be overcome by the system. The offset could due to contamination on the
current electrode surface. That can be corrected by cleaning the surface of the
electrode (see the section on Cleaning the Electrode). This could also be caused by
electrochemical corrosion in the electrode that occurs when the sealing property of
the adhesive fails. In this case, the electrode needs to be replaced.
2. Meter reading is not stable when the power is turned on
Check the
Mode
switch: if it is in V mode, the display will not be stable when the
electrode is not in the solution. This is normal. If the meter is in R mode, the meter
display should read zero unless the “Measure R” button is pressed. If it does not, the
meter is malfunctioning. Call WPI Technical Support for assistance.
3. Non-zero reading when measuring voltage
The electrode is dirty or not preconditioned. Clean the electrode as suggested above.
Soak the electrode in electrolyte over night with cable connected to
EVOM
. Make sure
the meter is turned off. After overnight soaking, adjust the Voltage zero to eliminate any
residual offset voltage.
4. Unstable resistance reading
Resistance measurements using the
STX2
electrode are sensitive to the position of
the electrode. Moving the electrode will cause the reading to change. This is normal.
However, if the electrode is held in a fixed position and the reading is unstable, there
could be several possible causes:
a.
The electrode is dirty and needs to be cleaned (see the section on Cleaning the
Electrode).
b.
The electrode and its cable are too close to a strong electromagnetic radiation
16 WORLD PRECISION INSTRUMENTS
