Teledyne 311 - Portable trace oxygen analyzer - Manual (Page 14)

WARNING: Evidence of damage due to tampering or mishandling will render the cell
warranty null and void.
5. TRANSDUCER AND TEMPERATURE COMPENSATION
The Micro-Fuel Cell has an inherent positive temperature coefficient, the effects of which have
been minimized through the implementation of a calibrated thermistor compensation circuit.
Internal electronic calibration is accomplished by TAI. However, should there by any doubt
concerning it, the following procedure can be used to recalibrate. Refer to Schematic.
1. Disconnect
cell.
2. Move range switch to “CAL” position.
3. Adjust R1 (designated as R1 on Schematic B14463 and designated on the A1 PCB
module assembly as R28) such that the output of A1, pin 6, measures between 0
and +0.5 mV, ideally +0.3 mV.
4. Adjust R2 (designated as R2 on Schematic B14463 and designated on the A3 PCB
module assembly as R28) for 0 ± 1 mV at output of A3, pin 6.
5. Verify that the offset is the same on all ranges.
6. Re-connect cell.
6. LEAK
TESTING
If a leak is suspected in the unit, DO NOT ATTEMPT TO TIGHTEN THE
DISCONNECT FITTINGS. THE FITTINGS ARE POTTED IN EPOXY AND
TIGHTENING THEM WILL BREAK THE SEAL!.
To check the leaks, TAI recommends one of the following procedures:
Procedure I:
1.
Purge the instrument down as low as possible.
2. Place the vent line in water and disconnect the sample.
3. Next, disconnect the vent line and place the range switch on the X100 range.
4. The unit should stay on the X100 range if there are no leaks.
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