Velleman DVM8681 - Manual (Page 3)

DVM8681 VELLEMAN - 3 -
b. Auto Power-Off
• This meter will switch off after approximately 20 minutes of inactivity.
• Disable this function by holding HLD and PWR simultaneously pressed before power-on. An “n” will briefly
appear onto the display. The function has been disabled. The function will be reactivated after every
power-off.
c. Automatic Temperature Compensation (ATC)
• Since pH values are temperature dependent, pH applications require some form of
temperature compensation to ensure standardized pH values. This meter automatically
corrects the pH values based on the temperature of the measured solution.
• Hold CAL and PWR simultaneously pressed before power-on. “°C” or “°F” will appear on
the display. Select your temperature unit with HLD and press CAL to save.
• “SA” will briefly appear on the display to indicate the selection has been saved. This
selection will be saved after power-off.
d. Calibrating your Meter
• Calibration is necessary and should be done regularly, even on a daily basis when using the meter often.
• Switch on your pH meter.
• Place the electrode into the pH 7 test solution first and into the pH 4 or pH 10 afterwards
(test solution available at your local chemist’s).
• Press CAL to enter the calibration mode. “CA” will briefly appear on the display. After a
few seconds “CAL” and the pH value will appear on the display indicating the meter has
been calibrated.
• The meter will display “En” if the calibration was not done correctly or if the probe could
not detect the test solution in the voltage range below. In this case, recalibrate as per
above.
pH 4.00 97mV….250mV
pH 7.00 -60mV….60mV
pH 10.00 -250mV….-97mV
• If the meter successfully recognizes the test solution, the solution pH value (4, 7 or 10) will appear on the
display. If the displayed value differs slightly from the supposed value, e.g. 4.01 instead of 4.00, press HLD
to change the value. The adjustable calibration range for pH 4 is 3.50 ~ 4.50, for pH 7 is 6.50 ~ 7.50 and for
pH 10 is 9.50 ~ 10.50.
• A stable value will automatically be saved.
5. Cleaning and Maintenance
• Avoid touching the probe with bare hands and keep it wet by moistening the sponge in the cap.
• Rinse the probe with tap water or better, de-ionized water after each measurement.
• Remove the batteries from the meter if not used for a long time.
6. Troubleshooting
• No display after power-on
Check the batteries. Replace them if necessary (see “2. Battery Installation”).
• Slow response
Clean the probe thoroughly with tap water and rinse with de-ionized water afterwards.