Teledyne T300, Operation Manual, Page: 285 / 426

Teledyne API – Model T300/T300M CO Analyzer Troubleshooting and Service
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12.5.7.6. PRESSURE/FLOW SENSOR ASSEMBLY
The pressure/flow sensor PCA, located on the top of the absorption bench, can be
checked with a voltmeter using the following procedure which, assumes that the wiring
is intact, and that the motherboard and the power supplies are operating properly:
1. For Pressure related problems:
•
Measure the voltage across C1 - it should be 5 ± 0.25 VDC.
If not, then the board is bad.
•
Measure the voltage across TP4 and TP1.
•
With the sample pump disabled it should be 4500 mV ±250 mV.
•
With the pump energized it should be approximately 200 mV less.
If the voltage is incorrect, then S1, the pressure transducer is bad, the board is bad, or
there is a pneumatic failure preventing the pressure transducer from sensing the
absorption cell pressure properly.
2. For flow related problems:
•
Measure the voltage across TP2 and TP1 - it should be 10 ±0.25 VDC.
If not, then the board is bad.
•
Measure the voltage across TP3 and TP1:
•
With proper flow (800 sccm at the sample inlet) this should be approximately
4.5V (this voltage will vary with altitude).
•
With flow stopped (sample inlet blocked) the voltage should be approximately
1V.
If the voltage is incorrect, the flow sensor is bad, the board is bad, or there is a leak
upstream of the sensor.
06864B DCN6314