YSI 6500 Environmental Process Monitor - Manual (Page 59)

Troubleshooting Section 6
6.3 CALIBRATION ERROR MESSAGES
Symptom: When attempting to confirm a dissolved oxygen sensor
calibration, an error message appears which indicates “High DO Charge”.
Possible Cause and Suggested Action: This message indicates a malfunction in the DO sensor that is
generally due to the roughness of the electrodes on the surface of the probe face. The charge
associated with the DO sensor must be in the range 25 to 100 or the error message will appear when
calibration is attempted. If this error message is encountered, remove the probe guard from the sonde
and resurface the DO probe according to the instructions in Section 2, Sondes, of the 6-Series Sonde
Operations Menu.. After resurfacing the probe, activate the DO charge parameter and confirm that
the value is within the acceptable range. After resurfacing, allow the sensor to run for at least 5
minutes before making a final evaluation of the charge value. If the charge value is in the acceptable
range after resurfacing, proceed with the calibration protocol. If resurfacing according to the
instructions does not result in a lowering of the charge, contact YSI authorized service for advice.
Symptom: When attempting to confirm a dissolved oxygen, pH, or
conductivity sensor calibration, an error message appears which indicates
“Out of Range”.
Possible Cause and Suggested Action: This message indicates that the output of the sensor being
calibrated does not conform to the normal range for this parameter. This problem could be due to
either a malfunctioning sensor or to a calibration solution that is out of specification. If this error
message is encountered, first assure that your pH buffers and conductivity standards have not been
contaminated and that your DO sensor is in air (DO % Cal) or in a solution of known dissolved
oxygen concentration (DO mg/L). Also be certain that you have entered the correct value for the
calibration solution. If the calibration error message continues to occur, contact authorized service to
determine whether the sensor in question needs to be replaced.
6.4 SENSOR ACCURACY AND REPEATABILITY PROBLEMS
Symptom: After extended deployment, any or all of the activated sensor
readings seem unreasonable or noisy.
Possible Cause and Suggested Action: The sonde probe compartment may have been fouled with
algae or other debris creating an isolated environment which is not representative of the bulk stream.
Remove the sonde from the stream completely and manually clean the sonde and sensors. Replace in
the stream and note if the readings return to reasonable values.
Symptom: Even after removal of debris from the sonde (see above), the
readings of some or all of the sensors are unusual and/or noisy.
YSI Incorporated 6500 Environmental Process Monitor 56