Teledyne GFC-7000T - Trace CO2 Analyzer - manual - Manual (Page 241)

Troubleshooting Model GFC7000TA Carbon Dioxide Analyzer
Teledyne Analytical Instruments 223
TEST
FUNCTIONS
INDICATED FAILURE(S)
SLOPE
Values outside range indicate
Contamination of the zero air or span gas supply
Instrument is miss-calibrated
Blocked gas flow
Contaminated or leaking GFC wheel (either chamber)
Faulty IR photo-detector
Faulty sample faulty IR photo-detector pressure sensor (P1) or circuitry
Invalid M/R ratio (see above)
Bad/incorrect span gas concentration due.
OFFSET
Values outside range indicate
Contamination of the zero air supply
Contaminated or leaking GFC wheel (either chamber)
Faulty IR photo-detector
10.1.3. Using the Diagnostic Signal I/O Function
The Signal I/O parameters found under the DIAG Menu (See Section 6.9.2 and Appendix A) combined
with a thorough understanding of the instrument’s Theory of Operation (found in Section 10) are useful for
troubleshooting in three ways:
 The technician can view the raw, unprocessed signal level of the analyzer’s critical inputs and
outputs.
 All of the components and functions that are normally under algorithmic control of the CPU can be
manually exercised.
 The technician can directly control the signal level of the Analog and Digital Output signals.
This allows the technician to systematically observe the effect of directly controlling these signals on the
operation of the analyzer. Below in Figure 11-2 is an example of how to use the signal I/O menu to view
the raw voltage of an input signal or to control the state of an output voltage or control signal. The
specific parameter will vary depending on the situation.