Teledyne t320u Manuale Utente

Troubleshooting and Service 

Teledyne API – Model T300/T300M CO Analyzer 

3.  If the relay has failed there should be no change in the voltage across pins 2 and 4 

or 3 and 4.  Note: K2 is in a socket for easy replacement.   

4.  If K2 checks out OK, the thermistor temperature sensor located on the optical bench 

near the front of the instrument could be at fault.   

  Unplug the connector labeled “Bench”, and measure the resistance of the 

thermistor.   

  At room temperature it should have approximately 30K Ohms resistance; near 

the 48

o

C set point it should have ~12K ohms.   

12.4.1.3. GFC WHEEL TEMPERATURE  

Like the bench heater above there are three possible causes for the GFC Wheel 
temperature to have failed. 

1.  The wheel heater has failed.   

  Check the resistance between pins 1 and 4 on the white five-pin connector just 

below the sample temperature sensor on the bench (pin 1 is the pointed end).   

  It should be approximately 275 ohms. 

2.  Assuming that the I

2

C bus is working and that there is no other failure with the relay 

board; the solid-state relay (K1) on the relay board may have failed.   

 Using 

the 

WHEEL_HEATER parameter under the signal I/O function, as 

described above, turn on and off K1 (D2 on the relay board should illuminate as 
the heater is turned on).   

  Check the AC voltage present between pin 1 and 4.   

 

 

 

3.  If the relay has failed there should be no change in the voltage across pins 1 and 4.   

  K1 is socketed  for easy replacement.   

4.  If K1 checks out OK, the thermistor temperature sensor located at the front of the 

filter wheel assembly may have failed.   

5.  Unplug the connector labeled “Wheel”, and measure the resistance of the 

thermistor.  The resistance near the 68°C set point is ~5.7k ohms.   

06864B DCN6314