SRS Labs QMS 100 Series, Руководство пользователя

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5-26 Component Replacement
SRS QMS Gas Analyzer
2. Set up in advance a clean dust-free working area where to carry out this procedure.
3. Turn off the RGA and disconnect the ECU from the probe.
4. Wait for the probe to cool down for at least 30 minutes after the emission is turned off. Severe
burns can result if the probe is handled too soon .
5. Without disconnecting the cover nipple from the vacuum port, remove the six bolts from the
feedthru flange at the end of the probe and slide the entire probe assembly out of the vacuum
system (Note the rotational orientation of the Feedthru Flange before removing the probe
assembly from the vacuum system so that the probe can be reassembled in the exact same way
at the end of the replacement procedure. Mark the side of the flanges with a permanent marker
if necessary.) The ionizer, the filter, and the detector are now fully exposed and easily
accessible.
Figure 4 Probe Removal for CDEM Replacement
6. Carry the probe to a clean, dust free area immediately. Avoid contamination using handling
procedures compatible with high vacuum/clean room requirements.
7. Hold the probe in a secure upright position and do a thorough visual inspection of the unit.
Check for loose, damaged, misaligned and severely contaminated components.
Carefully inspect the ionizer and, if any problems are detected, perform a filament and/or ionizer
replacement following the procedures described earlier in this chapter.
Inspect the CDEM for signs of arcing and contamination. A blue tinge is an indication of an
electrical arc while brown indicates contamination. A “burned” black color may indicate both
arcing and contamination have occurred. If excessive contamination is evident take the
necessary steps to identify and reduce contamination sources in the vacuum system.
8. CDEM Removal:
Note the position of all parts and their orientation before disassembly!
The CDEM consists of a straight, four-channel tube made out of glass, with a cone of the same
material attached to the front end. It is held upright, next to the FC, and away from the axis of
the analyzer, by a
clamp and a clip . The clamp wraps around the multiplier tube, and is
connected to a neighboring rod. It assures proper alignment of the cone and provides the
electrical connection to the High Voltage power supply. A hole on the side of the FC Shield
allows space for mounting the cone very close to the FC top. The
clip is spot welded to the
side of the FC shield and holds the lower end of the multiplier’s tube at ground. Chrome
electrical coatings, deposited at both ends of the multiplier provide the necessary electrical