The reference air pump is mounted on the 1630-2 PCB in the base of the Analyzer. The operation of the pump is
monitored by the Analyzer and alarms will be shown if a fault occurs. (“Pump Fail” alarm )
To replace the pump, unplug all the field wiring terminals. ie. Power connector, sensor connectors etc.
Unplug the 10 way and the 40 way ribbon connectors. Remove the 5 captive screws that retain the terminal PCB in the
base of the case. Remove the PCB from the case. The pump can now be un-screwed, and the wires un-plugged.
6.5 BACK-UP BATTERY REPLACEMENT
The back-up battery is contained within the battery-like real time clock/memory module, plugged into socket M1. It is
rated for an average service life of greater than ten years. The module is not re-chargeable and should be replaced
every three years with a stored transmitters with power off or every eight years with a transmitters which have had the
power on. The memory module must be purchased from Teledyne Analytical Instruments or an agent of Teledyne
Analytical Instruments.
After replacing the battery, re-enter all set-up mode functions.
6.6 ELECTRONIC REPAIRS
Electronic schematics are included in Appendix 4. A competent electronic technician could perform troubleshooting
with these schematics, aided by the Analyzer self-diagnostic alarms. It is recommended that service be performed on a
change-over circuit board basis. A fast turn-around or replacement service is available from Teledyne Analytical
Instrumentsor accredited service agents. Other service aids, including a test EPROM firmware package and sensor
input simulator are also available.
6.7 TEST EQUIPMENT REQUIRED
All measurements are simplified if a 9070 Analyzer is connected to the oxygen sensor. Readings can then be easily
taken of sensor impedance, EMF, temperature and percent oxygen. The Analyzer also provides proper heater control
for heated sensors.
First check all alarms on the Analyzer, allowing time for the sensor to heat up after switch on.
An instrument to measure sensor EMF and temperature is required. A 3 1/2 or 4 1/2 digit multimeter will perform both
measurements.
A separate temperature indicator to suit the sensor ‘K’ type thermocouple is also useful, although not necessary.
A cylinder of calibration gas is required, eg. 2.0 % oxygen in nitrogen. The cylinder should have a pressure and flow
regulator. Both of these are inexpensive devices available from gas supply companies. The calibration gas should be
chromatograph tested to an accuracy of 0.1 % oxygen.
6.8 TESTING AN OXYGEN SENSOR
With the sensor tip heated to approximately 720°C (1320°F), connect a digital multimeter to the sensor electrode
conductors, terminals 1 and 2. If a multimeter is not available, the EMF reading may be taken from the lower line of the
display. Apply approximately 300 cc (36 scfm) /minute of air to the inlet port. The multimeter should read zero
millivolts +
2.0 millivolts.
If not, then there is a problem with the sensor electrodes and the sensor needs refurbishing. Normally a faulty sensor
electrode is indicated with a high source impedance. This can be measured on the lower line of the 9070 display
To test the source impedance, use the sensor impedance display on the lower line. Refer to Section 5.5.29, Lower Line
Display Functions. If the impedance is above 3kΩ, then the electrode needs refurbishing.
Where a sensor electrode requires refurbishing it is suggested that they should be returned to Teledyne Analytical
Instrumentsor an accredited service organisation.
If the sensor tests reveal less than 2 mV offset and a good impedance reading, the next step is to apply a calibration gas.
The calibration gas should be inserted in the normal inlet port of the 9070, at the same flow rate as used when in use.
With the calibration gas flowing, the sensor should develop an EMF according to the tables in Appendix 1. If the EMF
reading is low then there may be insufficient calibration gas flow. Increase the calibration gas slightly until the reading
is correct. An excessive calibration gas flow will cause cooling on one surface of the sensor, giving temperature
differential errors on the sensor.
Teledyne Analytical Instruments 9070 Oxygen Analyzer Page 43
