IM 12D08N05-01E
7-2
<7. MAINTENANCE>
NOTE
Resistance due to fouling or to polarization does not effect the accuracy and operation of a
4-electrode conductivity measuring system. If an apparent increase in cell constant occurs
cleaning the cell will restore accurate measurement.
7.3 Cleaning methods
1. For normal applications hot water with domestic washing-up liquid added will be
effective.
2. For lime, hydroxides, etc., a 5 ...10% solution of hydrochloric acid is recommended.
3. Organic contaminants (oils, fats, etc.) can be easily removed with acetone.
4. For algae, bacteria or moulds, use a solution of domestic bleach (hypochlorite).
* Never use hydrochloric acid and bleaching liquid simultaneously. The release of the very
poisonous chlorine gas will result.
7.4 LCD adjustment
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Contrast adjustment
During the life of the analyzer the contrast of the display may fade. The contrast can be
adjusted using the potentiometer on the backside of the LCD board. This adjustment must
be done only by Yokogawa’s service personnel. The position is shown on the picture below.
For units manufactured after July 2007, the potentiometer is placed behind the little hole in
the LCD bracket as shown in Figure 3.4.
For units manufactured between April 2006 and April 2007, the potentiometer is located as
shown below.
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Touchscreen adjustment
CAUTION
A few years after using, the touchscreen may deviate from the correct position due to aging
deterioration of the touchscreen. When that happens, turn off power then on again. The
touchscreen will be calibrated automatically to the correct touch position at power on. It is
recommended to turn off power then on again when periodic maintenance.
CAUTION
Do not turn on power with the touchscreen pressed, otherwise inaccurate touch position
will occur. If it occurs, leave the touchscreen unpressed, turn off power then on again. The
touch position will be accurate.
