Teledyne 703E User Manual

1.  Measure the pressure on the inlet side of S1 with an external pressure meter. 

2.  Measure the voltage across TP4 and TP1.   

  The expected value for this signal should be: 

 

EXAMPLE:  If the measured pressure is 20 Hg-in-A, the expected voltage level between TP4 and 
TP1 would be between 2870 mVDC and 3510 mVDC. 

EXAMPLE:  If the measured pressure is 25 Hg-in-A, the expected voltage level between TP4 and 
TP1 would be between 3533 mVDC and 4318 mVDC. 

  If this voltage is out of range, then either pressure transducer S1 is bad, the board is bad or there is a 

pneumatic failure preventing the pressure transducer from sensing the absorption cell pressure 
properly. 

 

1.  Measure the pressure on the inlet side of S2 with an external pressure meter. 

2.  Measure the voltage across TP5 and TP1.   

  The expected value for this signal should be: 

   

EXAMPLE:  If the measured pressure is 25 psig, the expected voltage level between TP4 and TP1 
would be between 3470 mVDC and 4245 mVDC. 

EXAMPLE:  If the measured pressure is 30 psig, the expected voltage level between TP4 and TP1 
would be between 4030 mVDC and 4930 mVDC. 

  If this voltage is out of range, then either pressure transducer S1 is bad, the board is bad or there is a 

pneumatic failure preventing the pressure transducer from sensing the absorption cell pressure 
properly. 

  Measure the voltage across TP3 and TP1.   

  With proper flow (800 cc

3

/min through the photometer), this should be approximately 4.5V (this 

voltage will vary with altitude).   

  With flow stopped (photometer inlet disconnected or pump turned OFF) the voltage should be 

approximately 1V.   

  If the voltage is incorrect, the flow sensor S3 is bad, the board is bad or there is a leak upstream of 

the sensor.