YOKOGAWA PH72-21-E-AA, User Manual

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IM 12B03D02-01E
7-6
7. Troubleshooting
7.4 Other Conditions
• An alarm sounds
The alarm is set to sound at the preset alarm time. Refer to Section 5.3 (7), “Alarm time
setting (ALM) panel.”
• Beeps
The beep sound to acknowledge a key press can be enabled/disabled. Refer to Section
5.3 (9), “Set beep on/off (bZ.o) panel.”
• appears
This indicates that the electrode has deteriorated. The electrode may be used
continuously even after this mark appears. If a or message appears in
addition to this mark, however, replace the sensor with a new one immediately.
This mark will also appear when deteriorated or poor quality standard solutions are used
for calibration, when dirt or deposits are present on the electrode, or when calibration is
performed improperly. When it appears, perform acid cleaning (see Section 6.2) and
recalibrate using fresh standard solutions.
• appears
This does not indicate any failure if a sensor without a built-in temperature element (a
needle type or test tube size pH sensor) is used. If this mark appears, manually set the
temperature of a solution. (See Section 5.3 (2).)
If it appears even though a sensor with a built-in temperature element is used, the
temperature measuring circuit may have broken. In this case the meter performs
temperature compensation assuming that the solution temperature is 25
8
C. Therefore, the
bigger the difference between the actual temperature of the solution and 25
8
C, the bigger
the error between the displayed measured value and the true value. For reliable
measurement replace the sensor with a good one.
This mark will also appear if the sensor is not connected properly. Make sure that the
connectors are securely connected.