TELEDYNE API T703U - Using the Diagnostic Signal I;O Function

General Troubleshooting & Service Teledyne API T703/T703U Calibrator Operation Manual
158
TEST FUNCTION
DIAGNOSTIC RELEVANCE AND CAUSES OF FAULT CONDITIONS.
- The there is sufficient open space to the side and rear of instrument to allow adequate
ventilation.
PHOTO MEASURE
&
PHOTO REFERENCE
If the value displayed is too high the UV Source has become brighter. Adjust the variable
gain potentiometer on the UV Preamp Board in the optical bench.
If the value displayed is too low:
- < 100mV – Bad UV lamp or UV lamp power supply.
- < 2000mV – Lamp output has dropped, adjust UV Preamp Board or replace lamp.
If the value displayed is constantly changing:
- Bad UV lamp.
- Defective UV lamp power supply.
- Failed I
2
C Bus.
If the PHOTO REFERENCE value changes by more than 10mV between zero and
span gas:
- Defective/leaking switching valve.
PHOTO FLOW
Gas flow problems directly affect the accuracy of the photometer measurements and
therefore the concentration accuracy of cal gas mixtures involving O
3
and GPT mixtures.
- Check for Gas Flow problems.
PHOTO LAMP TEMP
Poor photometer temp control can cause instrument noise, stability and drift. Temperatures
outside of the specified range or oscillating temperatures are cause for concern.
Possible causes of faults are the same as PHOTO LAMP TEMP WARNING from Table 8-1
PHOTO SPRESS
The pressure of the gas in the photometer‟s sample chamber is used to calculate the
concentration of O
3
in the gas stream. Incorrect sample pressure can cause inaccurate
readings.
- Check for Gas Flow problems. See Section Table 8-1.
PHOTO STEMP
The temperature of the gas in the photometer‟s sample chamber is used to calculate the
concentration of O
3
in the gas stream. Incorrect sample temperature can cause inaccurate
readings.
Possible causes of faults are:
- Bad bench lamp heater
- Failed sample temperature sensor
- Failed relay controlling the bench heater
- Failed Relay PCA
- I
2
C Bus malfunction
- Hot Lamp
PHOTO SLOPE
Values outside range indicate:
Contamination of the Zero Air or Span Gas supply.
Instrument is miss-calibrated.
Blocked Gas Flow.
Faulty Sample Pressure Sensor or circuitry.
Bad/incorrect Span Gas concentration.
PHOTO OFFSET
Values outside range indicate:
Contamination of the Zero Air supply.
TIME
Time of Day clock is too fast or slow.
To adjust see Section 4.7.2.
Battery in clock chip on CPU board may be dead.
USING THE DIAGNOSTIC SIGNAL I/O FUNCTION 8.1.3.
The Signal I/O parameters found under the DIAG Menu combined with a
thorough understanding of the instruments Theory of Operation (found in Section
9) are useful for troubleshooting in three ways:
07223D DCN7107