Troubleshooting
Troubleshooting Guides
6-6
Model 43i Trace Level-Enhanced Instruction Manual
Thermo Fisher Scientific
Malfunction
Possible Cause
Action
Check all external plumbing and the
source of the sample to verify that the
SO
2
is not being adsorbed by the
sampling system. Lines carrying SO
2
must be made from clean Teflon or
stainless steel.
Detection circuit failure
Go to Diagnostics menu and run the
optical span test to verify PMT and
associated electronics.
Instrument is not properly
calibrated.
Go to the Calibration Factors menu and
verify that the SO
2
Background and SO
2
Coefficient are set appropriately.
Input board malfunction
Go to Service Menu and select Input
Board Test to verify A/D signal on each
range.
Signal cable failure
While viewing the Input Board Test
screen, set the gain to 100 and then
disconnect the signal cable from the
input board. The signal should drop
from a value above 1000 to near zero.
PMT failure
Check the PMT voltage (Service menu).
Flash lamp assembly
failure
Check the lamp voltage (Service menu).
Span calibration
coefficient outside
acceptable limits of
0.5 – 2.0.
Bad span gas
Verify quality of span gas.
System leak
Perform leak test.
Insufficient calibrator flow
Verify calibrator is providing a flow of at
least 0.8 LPM.
Excessive noise or
spikes on analog
outputs
Defective or low
sensitivity PMT
Check PMT voltage and run an optical
span test. Replace PMT with known
good unit if possible.
Defective input board or
BNC connection
Identify the defective component and
replace.
Noise pick-up by recorder
or data logger
Check analog cable shielding and
grounding.
Try to localize source of noise by
comparing analog signal to data
collected through RS-232 or Ethernet.
Poor linearity
Problem with calibrator
Verify accuracy of the multipoint
calibration system with an independent
flow meter.
