Using The Diagnostic Analog Inputs Function - Teledyne T750 User Manual

FUNCTION
If the Box Temperature is out of range (Box Temperature typically runs ~7°C warmer than
ambient temperature), make sure that:
Box Temp - The Exhaust-Fan is running.
- There is sufficient open space to the side and rear of instrument to allow adequate
ventilation.
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.
O3 Meas
If the value displayed is constantly changing:
&
- Bad UV lamp.
O3 Ref
- Defective UV lamp power supply.
- Failed I
If the O3 Ref value changes by more than 10mV between zero and span gas:
- Defective/leaking switching valve.
Gas flow problems directly affect the accuracy of the photometer measurements and
therefore the concentration accuracy of cal gas mixtures.
Photo Flow
- Check for Gas Flow problems.
Poor photometer temp control can cause instrument noise, instability and drift. Temperatures
outside of the specified range or oscillating temperatures are cause for concern.
Photo Lamp Temp
Possible causes of faults are the same as PHOTO LAMP TEMP WARNING from Table 8-1
The pressure of the gas in the photometer's sample chamber is used to calculate the
concentration of O
O3 Press
readings.
- Check for Gas Flow problems.
The temperature of the gas in the photometer's sample chamber is used to calculate the
concentration of O
readings.
Possible causes of faults are:
- Bad bench lamp heater
Sample Temp
- Failed sample temperature sensor
- Failed relay controlling the bench heater
- Failed Power distribution board
- I
2
- Hot Lamp
Values outside range indicate:
Contamination of the Zero Air or Span Gas supply.
Instrument is miss-calibrated.
O3 Slope
Blocked Gas Flow.
Faulty Sample Pressure Sensor or circuitry.
Bad/incorrect Span Gas concentration.
Values outside range indicate:
O3 Offset
Contamination of the Zero Air supply.
U
SING THE
The Analog Inputs found under the Utilities>Diagnostics menu combined with a thorough
understanding of the instrument's Theory of Operation (Section 9) are useful for
troubleshooting in that the technician can view the raw, unprocessed signal level, and
control some, of the calibrator's critical inputs and outputs. Ensure that the instrument is
in Standby mode (under Home>Generate).
136
DIAGNOSTIC RELEVANCE AND CAUSES OF FAULT CONDITIONS.
2 C Bus.
in the gas stream. Incorrect sample pressure can cause inaccurate
3
in the gas stream. Incorrect sample temperature can cause inaccurate
3
C Bus malfunction
D A
IAGNOSTIC NALOG
I F
NPUTS UNCTION
083730750B DCN8606