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Troubleshooting & Service T400 Ozone Analyzer Operator’s Manual
252
12.2. USING THE ANALOG OUTPUT TEST CHANNEL
The signals available for output over the T400’s analog output channel can also be used
as diagnostic tools. See Section 5.10 for instruction on activating the analog output and
selecting a function.
Table 12-3: Test Channel Outputs as Diagnostic Tools
TEST
CHANNEL
DESCRIPTION ZERO
FULL
SCALE
CAUSES OF EXTREMELY
HIGH / LOW READINGS
PHOTO
MEAS
Raw output of the
photometer during its
measure cycle
0 mV 5000 mV
PHOTO
REF
Raw output of the
photometer during its
reference cycle
0 mV 5000 mV
If the value displayed is:
- >5000 mV: The UV source has become brighter; adjust the
UV Detector Gain potentiometer.
- < 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 M/R switching valve.
O
3
GEN
REF
Raw output of the O
3
generator’s reference
detector
0 mV 5000 mV
Possible failure of:
- O
3
generator UV Lamp
- O
3
generator reference detector
- O
3
generator lamp power supply
- I
2
C bus
SAMPLE
PRESSURE
Pressure of gas in the
photometer
absorption tube
0 In-Hg-A 40 In-Hg-A
Check for Gas Flow problems.
SAMPLE
FLOW
Gas flow rate through
the photometer
0 cm
3
/min 1000 cc/m
Check for Gas Flow problems.
SAMPLE
TEMP
Temperature of gas in
the photometer
absorption tube
0 C 70 C
Possible causes of faults are the same as SAMPLE TEMP
from Table 12-2
PHOTO
LAMP
TEMP
Temperature of the
photometer UV lamp
0 C 70 C
Possible failure of:
- Bench lamp heater
- Bench lamp temperature sensor
- Relay controlling the bench heater
- Entire Relay PCA
- I
2
C Bus
- Hot” Lamp
O
3
SCRUB
TEMP
Temperature of the
optional Metal Wool
Scrubber.
0 C 70 C
Possible failure of:
- Scrubber heater or temperature sensor
- Bad or loose wiring TC input connector on relay PCA
- Incorrectly configured TC input (e.g. J-type instead of K-
type)
- AC Relay controlling the scrubber heater
- Entire Relay PCA
- I
2
C Bus
O
3
LAMP
TEMP
Temperature of the
IZS Option’s O
3
generator UV lamp
0 mV 5000 mV
Same as PHOTO TEMP WARNING
from Table 12-1
CHASSIS
TEMP
Temperature inside
the T400’s chassis
(same as BOX TEMP)
0 C 70 C
Possible causes of faults are the same as BOX TEMP
WARNING from Table 12-1
06870C DCN6332