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Model GFC7000E Instruction Manual TROUBLESHOOTING & REPAIR PROCEDURES
04584 Rev A1 187
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. A worksheet has
been provided in Appendix C to assist in recording the value of these test functions.
The following table contains some of the more common causes for these values to be out of
range.
Table 11-2: Test Functions - Indicated Failures
TEST
FUNCTIONS
(As Displayed)
INDICATED FAILURE(S)
TIME
Time of day clock is too fast or slow
To adjust see Section 6.6.
Battery in clock chip on CPU board may be dead.
RANGE
Incorrectly configured measurement range(s) could cause response problems with a
Datalogger or chart recorder attached to one of the analog output.
If the Range selected is too small, the recording device will over range.
If the Range is too big, the device will show minimal or no apparent change in readings.
STABIL
Indicates noise level of instrument or CO
2
concentration of sample gas (see Section 11.3.2
for causes).
CO2 MEAS
&
CO2 REF
If the value displayed is too high the IR Source has become brighter. Adjust the variable
gain potentiometer on the sync/demod board
If the value displayed is too low or constantly changing and the CO
2
REF is OK:
Failed multiplexer on the mother board
Failed sync/demod board
Loose connector or wiring on sync/demod board
Flow of purge gas to the GFC wheel housing may have stopped
If the value displayed is too low or constantly changing and the CO
2
REF is BAD:
GFC wheel stopped or rotation is too slow
Failed sync/demod board IR source
Failed IR source
Failed relay board
Failed
I
2
C buss
Failed IR photo-detector
MR RATIO
When the analyzer is sampling zero air and the ratio is too low:
The reference cell of the GFC wheel is contaminated or leaking.
The alignment between the GFC wheel and the segment sensor, the M/R sensor or both
is incorrect.
Failed sync/demod board
Flow of purge gas to the GFC wheel housing may have stopped
When the analyzer is sampling zero air and the ratio is too high:
Zero air is contaminated
Failed IR photo-detector
PRES
See Table 11-1 for SAMPLE PRES WARN
SAMPLE FL
Check for gas flow problems. see Section 11.1.6
SAMPLE
TEMP
SAMPLE TEMP should be close to BENCH TEMP. Temperatures outside of the specified
range or oscillating temperatures are cause for concern
BENCH
TEMP
Bench temp control improves instrument noise, stability and drift. Temperatures outside of
the specified range or oscillating temperatures are cause for concern. See Table 11-1 for
BENCH TEMP WARNING
WHEEL
TEMP
Wheel temp control improves instrument noise, stability and drift. Outside of set point or
oscillating temperatures are cause for concern. See Table 11-1 for WHEEL TEMP
WARNING
BOX TEMP
If the box temperature is out of range, check fan in the power supply module. Areas to the
side and rear of instrument should allow adequate ventilation. See Table 11-1 for BOX
TEMP WARNING.