33
O&M Manual
Rev-L (7/15)
Part 8 – Service
8.1
General
The information included in this section is intended to be used in an attempt to quickly
resolve an operational problem with the system. During any troubleshooting process, it
will save the most time if the operator can first determine if the problem is related to the
analyzer, sensor, or some external source. Therefore, this section is organized from the
approach of excluding any likely external sources, isolating the analyzer, and finally
isolating the sensor. If these procedures still do not resolve the operational problems,
any results the operator may have noted here will be very helpful when discussing the
problem with the factory technical support group.
8.2
External Sources of Problems
To begin this process, review the connections of the system to all external connections.
1.
Carefully examine sensor wiring connections for loose wiring or bad wire
stripping.
2.
Check sensor membrane for fouling. Look closely for signs of grease or
oil which may be present. Replace membrane and electrolyte, allow to
stabilize, and re-check. The procedure in Dissolved Oxygen Sensor
Assembly, in section 4.1, must be followed when replacing the
membrane.
8.3
Analyzer Tests
1.
Turn off power and remove sensor wiring. Re-apply power to the analyzer.
2.
Using the Simulate feature, check operation of analog outputs with a DVM.
3.
Check TC drive circuit. Connect a 1000 Ohm resistor across the BROWN and
GREEN terminals. The temperature reading should display approximately 0°C
and the dissolved oxygen reading should display approximately 0 ppm.
8.4
DisplayMessages
The Q45 Series instruments provide a number of diagnostic messages which indicate
problems during normal operation and calibration. These messages appear as prompts
on the secondary line of the display or as items on the Fault List.
