LI-COR LI7200RS, Инструкция по эксплуатации

Страница: 167 / 226

not always indicate a serious problem; the cooler may simply have not yet reached
the target temperature during instrument startup, or it may be out of range due to
external environmental conditions. Readings may still be OK. The sensor head may
not be attached to the LI-7550, or the IRGA cable may not be tight. Check cables
and wiring.
Chopper Temperature - If not OK, indicates the chopper temperature controller is
out of range, hot or cold. As with the Detector Temperature indicator above, this
may or may not indicate a serious problem. The chopper should be able to tem-
perature control when ambient is b50 and -25 °C. Check that the sensor
head cables to the LI-7550 are tight, and make sure the chopper temperature is not
set to Winter when measuring in high ambient temperatures.
Aux Inputs – If not OK, indicates that the two reference voltages on the LI-7550
analog circuit board cannot be checked properly. The LI-7550 needs service.
Head Pressure – If not OK, the pressure reading at the sensor head is outside of its
normal range. A service indication can also be caused by a loose or missing cable
between the LI-7550 and the sensor head.
Inlet T - If not OK, the temperature reading at the sensor head inlet is outside of its
normal range. This can be caused by a loose or missing cable between the LI-7550
and the LI-7200/RS sensor head, or the inlet thermocouple has been broken.
Outlet T - If not OK, the temperature reading at the sensor head outlet is outside of
its normal range. This can be caused by a loose or missing cable between the LI-
7550 and the LI-7200/RS sensor head, or the outlet thermocouple has been broken.
Test Point Values
The
Test Points
tab displays voltages and raw counts of a variety of diagnostic test
points. Though primarily for LI-COR technician reference, values outside of the
normal range may give you an indication of where problems may be originating.
Section 7. Software Reference
7-29 Test Point Values