Teledyne 9110AH - Nitrogen oxides analyzer - Manual (Page 159)

TELEDYNE Model 9110AH NO
X
Analyzer Operator Manual, 01620, Rev. F
9-43
9.3.4 Status/Temp Board
The Status/Temp Board is a multifunction board that:
1. Converts the resistance readings of the thermistors to a voltage
2. Amplifies and scales the thermocouple voltage for the V/F card
3. Provides status output circuitry
4. Provides circuitry for contact closure inputs
5. Provides circuitry for display brown-out/reset at low line voltage
6. Provides circuitry for 4-20 mA outputs
9.3.4.1 Temperature Amplifier Section
The 4 thermistor amplifiers that convert resistance into voltage monitor:
1. Reaction Cell temperature
2. Heated Orifice block
3. Box temperature
4. Spare
The voltages of the thermistor and thermocouple amplifier outputs are brought out to test
points on the edge of the board. Refer to the schematic in the Appendix for details. The
voltages can also be read using the DIAGNOSTIC - SIGNAL I/O feature. See Table 9-4 for
details.
Thermistor Temperature Amplifier Adjustments
The 4 temperature amplifiers are controlled by a common pot (R34) on the upper edge of the
card.
If the temperature readouts are in error:
1. Locate the Box temp thermistor on the board and place a thermometer near the thermistor.
2. Select the BOX TEMP - TEST function on the front panel.
3. Adjust R34 until the front panel readout matches the thermometer readout. This will cause
all of the readouts to accurately measure their respective temperatures.
Converter Thermocouple Amplifier Adjustments
The converter temperature is sensed by a Type K thermocouple. The cold junction
compensation and signal conditioning are done on the Temp/Status board.