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Model GFC7000E Instruction Manual TROUBLESHOOTING & REPAIR PROCEDURES
04584 Rev A1 188
Table 11-2: Test Functions - Indicated Failures (cont.)
TEST
FUNCTIONS
(As Displayed)
INDICATED FAILURE(S)
PHT DRIVE
If this drive voltage is out of range it may indicate one of several problems:
- A poor mechanical connection between the various components in inside the detector
housing
- An electronic failure of the IR Photo-Detector’s built-in cooling circuitry, or;
- A temperature problem inside the analyzer chassis. In this case other temperature
warnings would also be active such as BENCH TEMP WARNING or BOX TEMP
WARNING.
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
11.1.3. 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 instruments theory of operation (found in Chapter
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 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.