Servomex 01440002D, Service Manual

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01440D Light Industrial Gas Analyser Service Manual. 2.6
2.3.3 Adjusting the Transducer Gain
It may be necessary to adjust the Span of the transducer if the altitude of use
is greater than about 1200m (4000ft) above sea level.
1.
Carefully remove foam cover from transducer.
2. Adjust the FINE SPAN pot on the top of the transducer fully
clockwise. The potentiometer will ‘click’ when it reaches the end.
3. Adjust the SPAN on the front panel fully clockwise.
4. Connect an air supply to the analyser, flow or pressure rates as per
section 2.2.
5. Adjust the COARSE SPAN pot on the top of the transducer, so that
the front panel displays a nominal 120% of air, approximately 25.1%
O
2
.
6. Refit the foam cover of the transducer and allow the analyser to
stabilise.
7. Adjust the SPAN on the front panel so that the display reads 20.9
±
0.1% O
2
.
2.3.4 Replacing the Thermal Fuse Assembly and/or Heater Disc
1. Remove the Transducer as described in section 2.3.1.
2. If replacing the heater disc, remove the protective backing from the
new heater disc and press firmly onto the base of the transducer.
Ensure transducer base is clean.
3. Refit transducer as described in section 2.3.1. Refit the foam cover
of the transducer.
4. After replacing the thermal fuse assembly or heater disc, the
transducer temperature should be re-checked. Connect a voltmeter
to pins 7 and 8 (0V) on SK5. When the instrument has warmed up,
adjust RV1 on control PCB 1420/915 so that the reading is 323
±3mV.