Varian 990 dCLD II, Operation Manual

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Model 990 dCLD II Component Leak Detector
3-17
When the ion source filament is successfully lit, the SPEC TUBE LED illuminates steadily,
the READY line in the discrete I/O is active and, after a short time for verification that the
ion source filament remains lit, the FILAMENT FAULT line in the discrete I/O becomes inac-
tive. If you repeatedly issue the ?STATUS<CR> inquiry during this process, you see the
response change from containing RDY/ to RDY and FLT, and, after a short time, FLT/.
The system is ready when the 3 LEDs on the control unit front panel remain steadily lit.
If the vacuum system has been at atmosphere or the electronics have been off for longer
than a few minutes but less than a few hours, a wait of approximately 30 minutes is recom-
mended so that the vacuum system and spectrometer tube can stabilize. During the stabili-
zation period, the ZERO signal drifts, making zeroing and calibrating difficult.
NOTE
Allow approximately 30 minutes for the system to stabilize
before running any tests if it has been off or IDLE for more than
a few minutes.
3.4.1 Start up Indications on the Optional Front Control Panel
If the optional front control panel is installed, the leak detector is ready for operation when
the SYSTEM READY indication appears on the Home Screen, the test mode is displayed in
the line above SYSTEM READY and the LED lights above the TEST/HOLD button (which is
inoperable on the 990 dCLD II). For more information see Section 4.4, “Touch Panel Home
Screen”. If the 990 dCLD II is being started after a long period of being off (several hours), it
can take up to 30 minutes to stabilize and provide reliable, quantitative leak rate readings.
3.4.2 Calibration
Calibration of the 990 dCLD II should be checked at least once every shift using a known
helium leak at a known temperature, such as the internal calibrated leak supplied with the
990 dCLD II. A pressure burst in the spectrometer tube, a blown Ion Source filament, a large
temperature change (over 10 °C), a power outage, contamination, or helium buildup in the
vacuum system are all factors that could affect calibration. The value of the calibrated leak
should be as close as possible to the decade most used during testing. This enhances the
accuracy of the leak detector.
To perform a calibration, set the parameters previously described in Section 3.3.1 “Parame-
ters and Operating Modes” on page 3-7 and then issue the CALIBRATE<CR> command.
When calibration is complete, the systems should respond
yes , to ?CALOK<CR>.