￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
6 Troubleshooting
884 Professional VA
￭￭￭￭￭￭￭￭
77
Problem
Cause
Remedy
The reference electrode is
not filled sufficiently (inside
and outside).
Top up the reference electrode
The reference electrode's
diaphragm is partially or
completely blocked (e.g.
from precipitation caused
by incompatible solutions
like KCl as a bridge electro-
lyte and HClO
4
as an elec-
trolyte in the measuring
solution).
Ensure the compatibility of the chemistry.
Replace the bridge electrolyte if necessary
(such as using a NaCl or KNO
3
solution in place
of KCl).
The electrolyte solution is
too old.
Produce new electrolyte solution. Organic
additives may only last 1 day or less.
Unstable or abnor-
mally low base cur-
rent in the pA range
(with MME pro).
The electrode drips contin-
uously.
￭
Check the MME pro.
￭
Adjust the needle and capillary.
￭
If necessary, replace the capillary or needle
(see the
Multi-Mode Electrode pro docu-
ment (8.110.8018XX)
).
The tapping mechanism on
the VA stand base is not
functioning correctly.
￭
Check the positioning of the capillary in the
MME pro. The capillary has to be centered
in the retaining screw.
￭
The retaining screw is too loose or tight-
ened too tightly: Use the wrench for the
MME (6.1247.220) to tighten the retaining
screw to the correct torque.
The gas pressure is set
incorrectly.
Set the gas pressure (1 - 1.2 bar; 14.5 - 17.4
psi; 0.1 - 0.12 MPa).
The gas pressure is unsta-
ble.
The gas pressure must hardly change during
the measurement. This can only be ensured if
a high-quality pressure relief valve is used and
the tubing connection between the pressure
relief and the instrument is not extended.
The concentration to be
determined is substantially
higher than assumed.
￭
Reduce the deposition time.
￭
If the application permits, change the elec-
trode type (e.g. HMDE to SMDE or DME).
￭
Reduce the sample volume.
Summary of Contents for 884 Professional VA
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