4690 Series
Turbidity systems
10 Fault Finding
IM/4690–EN Rev. A
35
10 Fault Finding
10.1 Error Messages
If erroneous or unexpected results are obtained, the fault may be indicated by an error message – see Table 10.1. The majority of
problems are overcome by thorough cleaning of the flowcell optical windows and / or a sensor calibration.
Error Message
Description and Remedy
Cal Fail
Indicates that the expected step change between a zero and span calibration was not produced by the
sensor (zero response from the sensor).
1. Repeat calibration.
2. If using a dry calibration standard, ensure that the optical windows on the dry standard are clean
and dry.
3. If using solutions:
Check that the flowcell has been thoroughly cleaned and rinse well between solutions
Check both zero and formazine solutions
4. Check electrical connections to sensor.
5. Using a suitable voltmeter, check the sensor 12 V supplies, both at the analyzer terminals and
sensor junction box – see Table 4.1 on page 14 for details.
6. Check the analyzer's response to an electrical input by injecting 0 and 3 V into the following
terminals and noting the reading displayed in
Sensor Voltage
in the
Operating
page (see Section
Wall- / pipe-mount–ve to terminal 7 +ve to terminal 4
Panel-mount –ve to terminal 6 +ve to terminal 9
Small errors in displayed voltage can be removed by electrical calibration. Large errors indicate an
electronic fault.
Cleaner Fail
Indicates that the analyzer was unable to detect the correct operation of the wiper unit; either the wiper
unit did not rotate or failed to park in the correct position.
1. Check the electrical connections to the sensor.
2. Using a suitable voltmeter, check the sensor 12 V supplies, both at the analyzer terminals and
sensor junction box – see Figs 4.4, 4.5 and 4.8 on pages 14, 15 and 17 for connection details.
3. Check operation of the wiper unit by disconnecting the white lead from the analyzer terminal block
(Cleaner Initiate signal) and touching it briefly to the 0 V terminal – see Table 4.1 on page 14 for
details. This initiates a cleaning cycle, that can be observed when the wiper unit is removed from the
flowcell.
NV Memory Error
Indicates that the contents of the nonvolatile memory has not been read correctly during power up. To
rectify the problem, switch off the power, wait 10 seconds and switch on again. If the problem persists
contact the Company.
Table 10.1 Error Messages
