Teledyne t320u Manual Do Utilizador

Teledyne API – Model T300/T300M CO Analyzer 

Troubleshooting and Service 

12.4.1.4. IR PHOTO-DETECTOR TEC TEMPERATURE 

If the PHT DRIVE test parameter described in Table 11-3 is out of range there are four 
possible causes of failure.   

1.  The screws retaining the IR photo detector to the absorption bench have become 

loose.   
  Carefully tighten the screws, hand-tight and note whether, after the analyzer has 

come up to operating temperature, whether the PHT DRIVE voltage has 
returned to an acceptable level.   

2.  The two large transistor-type devices mounted to the side of the Absorption Bench 

have come loose from the bench.   
  Tighten the retaining screws and note whether there is an improvement in the 

PHT DRIVE voltage. 

3.  The photo-detector has failed.  Contact the factory for instructions. 
4.  The sync demodulator circuit board has failed.  Contact the factor for instructions. 

12.4.2. EXCESSIVE NOISE 

Noise is continuously monitored in the TEST functions as the STABIL reading and 
only becomes meaningful after sampling a constant gas concentration for at least 10 
minutes.  Compare the current STABIL reading with that recorded at the time of 
manufacture (included in the T300/T300M 

 

Final Test and Validation Data Sheet,P/N 

04271 shipped with the unit from Teledyne API).   

1.  The most common cause of excessive noise is leaks.  Leak check and flow check 

the instrument described in Section 11.3.3 and 11.3.4.   

2.  Detector failure – caused by failure of the hermetic seal or over-temperature due to 

poor heat sinking of the detector can to the optical bench.   
  In addition to increased noise due to poor signal-to-noise ratio, another indicator 

of detector failure is a drop in the signal levels of the CO MEASURE signal and 
CO REFERENCE signal. 

3.  Sync/Demod Board failure.  There are many delicate, high impedance parts on this 

board.  Check the CO MEAS and CO REF Test Functions via the Front Panel 
Display. 

4.  The detector cooler control circuit can fail for reasons similar to the detector itself 

failing.  Symptoms would be a change in MR RATIO Test Function when zero air is 
being sampled.   

5.  Also check the SIGNAL I/O parameter PHT DRIVE.    

  After warm-up, and at 25

o

C ambient, if PHT DRIVE < 4800 mV, the cooler is 

working properly.   

 If 

PHT DRIVE is > 4800 mV there is a malfunction. 

6.  The +5 and 

15 VDC voltages in the T300/T300M are provided by switching power 

supplies.   

06864B DCN6314