083730300A DCN8101 Maintenance and Service 115
SAMPLE
PRESSURE
WARNING
Sample Pressure is <10 in-Hg or
> 35 in-Hg
Normally 29.92 in-Hg at sea level
decreasing at 1 in-Hg per 1000 ft
of altitude (with no flow – pump
disconnected).
If sample pressure is < 10 in-hg:
Blocked particulate filter
Blocked sample inlet/gas line
Failed pressure sensor/circuitry
If sample pressure is > 35 in-hg:
Pressurized sample gas. Install vent
Blocked vent line on pressurized sample/zero/span gas supply
Bad pressure sensor/circuitry
SAMPLE TEMP
WARN
Sample temperature is < 10
o
C or
> 100
o
C.
Ambient temperature outside of specified range
Failed bench heater
Failed bench temperature sensor
Relay controlling the bench heater
Failed relay board
2
SOURCE
WARNING
Occurs when CO Ref is <1250
mVDC or >4950 mVDC.
Either of these conditions will
result in an invalid M/R ratio.
Failed sync/demod board
If status LEDs on the sync/demod board ARE flashing the
cause is most likely a failed:
IR source
Relay board
I
2
C bus
SYSTEM RESET
The computer has rebooted.
This message occurs at power on. If you have not cycled the
power on your instrument:
Failed +5 VDC power,
Fatal error caused software to restart
WHEEL TEMP
WARNING
The filter wheel temperature is
controlled at 68 ± 2
°
C
Blocked cooling vents below GFC Assembly. Make sure that
adequate clear space beneath the analyzer.
Analyzer’s top cover removed
Wheel heater
Wheel temperature sensor
Relay controlling the wheel heater
Entire relay board
I
2
C bus
5.7.3 FAULT DIAGNOSIS WITH DASHBOARD FUNCTIONS
Besides being useful as predictive diagnostic tools, the test functions viewable from the
front panel can be used to isolate and identify many operational problems when
combined with a thorough understanding of the analyzer’s Theory of Operation (see
Section 6).
The acceptable ranges for these test functions are listed in the “Nominal Range” column
of the analyzer Final Test and Validation Data Sheet (T300, P/N 04307 and T300M, P/N
04311) shipped with the instrument. Values outside these acceptable ranges indicate a
failure of one or more of the analyzer’s subsystems. Functions whose values are still
within the acceptable range but have significantly changed from the measurement
recorded on the factory data sheet may also indicate a failure.
The following table contains some of the more common causes for these values to be out
of range.