Hach-Lange 1720E Low Range Turbidimeter - Manual (Page 34)

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Troubleshooting
Table 5 presents sensor warnings displayed in the Event Log, possible causes, and
corrective actions.
Table 6 presents additional malfunctions which may not be recorded in the Event Log.
Table 5 General Troubleshooting
Sensor Warning Possible Cause Corrective Action
Bad Lamp
Lamp burned out Replace the lamp. See section 6.4.3 on page 27 .
Lamp unplugged Restore connection
+12 V connection loose at controller Restore connection
Dislodged lamp Reinstall lamp
Bad circuit board in turbidimeter head Contact the Customer Service Department.
Low Signal
Photocell coated/dirty
See section 6.4.1 on page 26 .
Contact the Customer Service Department.
Photocell wires disconnected Reconnect wires
Photocell broken/cracked
Replace photocell
Contact the Customer Service Department.
Lens coated/dirty Clean the lens using isopropyl alcohol and a cotton swab.
Obstructed light path Remove obstruction
See Bad Lamp causes above See Bad Lamp corrective actions above
Bad System Voltage
Improper wiring at controller Refer to section 3.1 on page 9 .
Turbidimeter head cable shortened to
improper length
Contact the Customer Service Department.
Fluctuation in voltage Turn instrument power off and back on.
Bad circuit board in turbidimeter head Contact the Service Department
A/D Converter Timeout
Fluctuation in voltage Turn instrument power off and back on.
Bad circuit board in turbidimeter head Contact the Customer Service Department.
High Dark Counts
Light Leak—Turbidimeter head not on
turbidimeter body or calibration
cylinder during Power Up or Zero
Electronics Make sure the turbidimeter head is on the turbidimeter
body and properly aligned and repower instrument or
perform ZERO ELECTRONICS in the CALIBRATION
MENU.
Light Leak—Turbidimeter head not
properly aligned on the turbidimeter
body or calibration cylinder during
Power Up or
Zero Electronics
Make sure the turbidimeter head is properly aligned and
repower instrument or perform ZERO ELECTRONICS in
the CALIBRATION MENU.
Photocell broken/cracked Contact the Customer Service Department.
Table 6 Additional Malfunctions Not Recorded in the Event Log
Symptom Possible Cause Corrective Action
Continuous Underrange The calibration standard was either
improperly prepared or was unstable at
the time the calibration was accepted.
Verify the accuracy of calibration standards and
recalibrate the instrument. See Low Signal in
Table 5 .
Continuous Overrange
(100 NTU) The calibration standard was either
improperly prepared or was unstable at
the time the calibration was accepted. Verify the accuracy of calibration standards and
recalibrate the instrument.
Erratic Readings Inadequate bubble removal from sample Verify the accuracy of calibration standards and
recalibrate the instrument.
Increase the signal averaging time to a longer interval.
Make sure the Bubble Reject feature is turned on.
Slow the flow of sample into the instrument.