Combustion Oxygen Monitor
Endura AZ20 Series Probe 3 Troubleshooting – Quick Checks
6 IM/AZ20M–EN Rev. B
3 Troubleshooting – Quick Checks
Troubleshooting diagnostics are displayed on the transmitter –
refer to the transmitter User Guide (IM/AZ20E–EN). Where a
diagnostic fault is traced to the probe, it may be possible to
identify and rectify the fault. After any rectification, the system
must be recalibrated.
The following checks can be used to troubleshoot the cause of
probe failure quickly:
checking heater resistance – refer to Section 3.3, page 7
checking thermocouple / electrode assembly resistance –
refer to Section 3.4, page 7
checking cell isolation – refer to Section 3.5, page 8
3.1 Equipment Required
Digital multimeter (10 M input impedance on mV ranges).
3.2 Pre-check Requirements
1. The probe does not function properly unless the correct
reference air is applied – refer to the probe User Guide
(IM/AZ20P–EN).
2. Isolate the probe / transmitter system from mains power
before performing checks.
Referring to Fig.3.2:
3. At the probe, unscrew and remove the end cap
A and
unplug the 9-way terminal plug B from the 9-way
terminal block
C by unscrewing the 2 x M3 plug retaining
screws
D.
4. Proceed to Section 3.3, page 7.
Warning.
Dangerous voltages are present in the probe head
across the heater terminals
A (brown and blue) –
refer to Fig. 3.1.
Fig. 3.1 Heater Terminals in Probe Head
Fig. 3.2 Disconnecting the 9-way Terminal Plug
Note. If the probe has AutoCal, a 6-way terminal
block / plug (not shown) is fitted to the terminal plate.
It is not necessary to unplug the 6-way terminal plug
to perform initial checks.
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