Metrohm 894 Professional CVS - Manual (Page 91)

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7 Troubleshooting
894 Professional CVS
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7 Troubleshooting
7.1 894 Professional CVS
Problem Cause Remedy
An electrode cable
has broken. The cable has accidentally
been jammed in the mea-
suring head cover or a
cable contact has been
kinked. Replace the electrode cable set (see Chapter
6.5, page 76).
Conditioning takes a
long time. The reference electrode is
not yet equilibrated. After maintenance of the reference electrode,
wait for at least 20 min before starting a mea-
surement.
The working electrode is
contaminated. Condition the working electrode in pure VMS.
The electrode tip of the
working electrode has
been in use for a long
period. ￭ Immerse the electrode tip in c(NaOH) =
0.5 mol/L for approx. 10 min and then
thoroughly rinse with distilled water.
￭ Replace electrode tip if necessary.
VMS is contaminated. Check reagents for purity. (Only reagents of
sufficient purity, i.e. > 99%, should be used.)
The water quality is poor. Use distilled water, type-II grade (ASTM
D1193-91) or higher.
The measuring solution has
been contaminated as a
result of diffusion. No infeed tubing other than the fourfold micro
dosing tip (6.1824.000) may be immersed in
the measuring solution.
Solution is leaking
between the mea-
suring instrument
and the measuring
head. The measuring head is not
correctly locked in place on
the measuring head arm. Let the measuring head snap into place. The
click must be audible.
The sealing rings have
aged or are defective. Contact the Metrohm Service department.
The electrode test
fails. One or several electrodes
are not connected. Check the electrode cable connections.
One or several electrodes
are defective. Perform maintenance in accordance with the
electrode leaflet.