Teledyne 200AH 用户手册

 

2.  Check instrument electronics. 

A.  Do ELEC TEST procedure in DIAGNOSTIC menu Section 9.1.3.2. 

B.  Do OPTIC TEST procedure in the DIAGNOSTIC menu Section 9.1.3.3. 

If the M200AH passes ET and OT that means the instrument is capable of detecting light and 
processing the signal to produce a reading. Therefore the problem is in the pneumatics. 

3.  Check ozone generator subsystem. Do diagnostic test of ozone generator subsystem, see 

1.  Miss-calibration. The 'zero' gas that was used to zero the M200AH contained some NO gas - 

that is it had more NO gas than that of the sample air. Also, doing a zero calibration using 
sample air. 

2.  Reaction cell contamination - If NO/NO

X

 OFFSET - TEST functions are greater than 50 mV, 

this indicates reaction cell contamination. 

3.  Check for leaks. 

4.  Corruption of the AutoZero filter. If a significant signal was detected during the AutoZero 

cycle, that higher reading can enter the AutoZero filter. The value of the AutoZero filter is 
subtracted from the current reading, thus producing a negative reading. High AutoZero 
readings can be caused by: 

A.  Leaking AutoZero valve. 

B.  Electronic fault in the preamp causing it to have a voltage on the PMT output pin during 

the AutoZero cycle. 

C.  Reaction cell contamination causing high background (>40 mV) light readings. 

D.  Broken PMT temperature control circuit, allowing a high zero offset. 

After fixing the cause of the high AutoZero readings, the M200AH will take 15 minutes for the 
filter to clear itself. 

Common reasons for excessive noise are: 

1.  Leak in pneumatic system. 

2.  Light leak - check the sensor module with strong light. Check for missing 0-rings in Sensor 

Assembly.