Teledyne GFC-7001E - Trace CO Analyzer - Manual (Page 271)

Troubleshooting & Repair Model GFC7001E Carbon Dioxide Analyzer
Teledyne Analytical Instruments 271
The following table contains some of the more common causes for these values to be out of range.
Table 13-2: 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 6.5.4.
Battery in clock chip on CPU board may be dead.
RANGE
Incorrectly configured measurement range(s) could cause response problems with a Data logger 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 concentration of sample gas (see Section 13.4.2 for causes).
CO MEAS
&
CO REF
If the value displayed is too high the IR Source has become brighter. Adjust the variable gain potentiometer on
the sync/demod board (see Section 13.5.6.1).
If the value displayed is too low or constantly changing and the CO REF is OK:
 Failed multiplexer on the mother board
 Failed sync/demod board
 Loose connector or wiring on sync/demod board
 If the value displayed is too low or constantly changing and the CO 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 bus
 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
When the analyzer is sampling zero air and the ratio is too high:
 Zero air is contaminated
 Failed IR photo-detector
PRES See Table 13-1 for SAMPLE PRES WARN.
SAMPLE FL Check for gas flow problems (see Section 13.2).
SAMP 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. Table 13-1 for BENCH TEMP WARNING.
WHEEL
TEMP
Wheel temp control improves instrument noise, stability and drift. Outside of set point or oscillating
temperatures are causes for concern. See Table 13-1 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 13-1 for BOX TEMP WARNING.