4-21
Model 979 Series Helium Mass Spectrometer Leak Detector
DRAFT 9/15/03
7. Gently slide the ion source out of the spectrometer tube body (Figure 4-12 on
page 4-13).
NOTE
Dark carbon-like deposits around the ion source filament
and/or a rainbow-like discoloration on the inside walls of the
ion source cavity indicate that the spectrometer tube has been
operated at too high a pressure. This can occur from a system
pressure leak or transferring into test at too high a pressure.
8. Examine the ion source (Figure 4-13 on page 4-14) and cavity for deposits and
discoloration. If either is discolored or dirty contact Vacuum Technologies Customer
Service at 1-800-8VARIAN.
If Customer Service recommends a complete spectrometer tube overhaul, follow the
procedure in Section 4.3 “Spectrometer Tube Overhaul” on page 4-4.
9. When examination is completed, properly dispose of the ion source or return it to
Vacuum Technologies for exchange.
4.4.1 Reassembly
1. Replace the ion source (see Figure 4-24 on page 4-19).
NOTE
The ground slit plate has a hole in it that must be aligned with
the hole on the bottom of the spectrometer tube body ion
source cavity
➂
(Figure 4-24).
CAUTION
The ion source must be aligned so that its alignment pin
➃
(Figure 4-24) falls in the center of this hole.
A short could result at power up if the alignment pin touches
the sides of the alignment hole.
2. Replace the ion source header. Align the grooves with the legs on either side of the
center post and to the back of the spectrometer tube. Tighten the 4 Phillips screws.
3. Replace the ion source connector. It is keyed to go on only one way.
4. Close the vent on the turbo pump by turning the knurled nut 1/4 turn clockwise.
5. Close the front cover being careful not to pinch any wires. Replace and tighten the 2
Phillips screws.
Summary of Contents for 979 Series
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