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Teledyne API Model 200AU NO
X
Analyzer Instruction Manual, 02293, Rev. F
9-2
3. Check the TEST functions:
A. Compare the TEST functions to the factory values in Table 2-1. This will often provide
important clues as to the problem.
B. Pay special attention to the NO and NO
x
slopes:
C. The slopes are the software equivalent of the span pot on an analog instrument. If the
slopes are not 1.0 ± 0.3, the gain has changed.
D. Check the Pre-reactor - PREREACT - reading in the TEST functions. Compare it to the
value in the factory checkout Table 2-1. If the reading is significantly greater than the
factory test value, the reaction cell could be contaminated or there could be a light leak in
the cell. Verify this fault by turning the ozone generator off and see if the reading drops
more than 25 mV.
E. Check for a change in cell pressure (vacuum) - compare to value in Table 2-1. - possible
causes:
1) Partially plugged ozone killer
2) Change of pump or malfunctioning pump
3) Plugged pneumatics
4) Change in altitude
4. Check for pneumatic leaks - perform the leak check procedure in Section 8.7. If slopes
are different from each other by > .1, this usually indicates a leak in the switching (NO/NO
x
)
valve or improper calibration.
5. Check for light leaks - Turn off the ozone generator, then wait 7 minutes. If the reading
drops significantly, the reaction cell is contaminated. If not, a light leak is indicated.
6. Incorrect span gas concentration - this could come either from the calibrator or entering
the expected span gas concentration in the M200AU incorrectly, see Table 7-3.
7. If the instrument does not respond to span gas, check Section 9.2.3.
The above should get you started in diagnosing and repairing the most common faults. If these
reasons have been eliminated, the next thing to do is a Factory Calibration covered in Section
9.1.6 or check Section 9.2 for other fault diagnosis. If difficulties persist, contact our service
department. The 800 telephone number is on the cover page of this manual.