INFICON UHV Bakeable Sensor - Manual (Page 50)

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UHV Bakeable Sensor Operating Manual
5.1.3.2 Electrical Continuity Check
1 Select the DMM ohmmeter function and a low resistance scale.
NOTE: The resistance specifications in the following steps do not take into
account the resistance of the Digital Multimeter probes. Touch the
probe tips together and note the resistance reading. Compensate for
probe resistance by subtracting probe resistance from resistance
measurements, or by zeroing the ohmmeter while the probes are
touching.
2 Remove the ceramic retainer and crystal from the crystal holder, and then
reinstall the ceramic retainer into the crystal holder without a crystal.
3 Measure the resistance between the ceramic retainer and crystal holder as
shown by
Figure 5-2 .
 If resistance is less than 0.3 ohm (  , continue to step 4.
 If resistance is more than 0.3  , correct the cause of the high resistance
before continuing to step 4. Check the following:
 Cleanliness of the crystal seating surface inside the crystal holder (refer
to
section 4.3.2 on page 4-6 ).
 Angle of the leaf spring on the ceramic retainer (refer to section 4.3.1
on page 4-5 ).
 Verify that the leaf spring and circular plate on the ceramic retainer are
tightly held together by the rivet.
Figure 5-2 Resistance between ceramic retainer and crystal holder
4 Install the crystal holder with ceramic retainer into the bakeable sensor.
5 At the BNC connector on the bakeable sensor feedthrough, measure the
resistance between the center contact and shield (refer to
Figure 5-1 ).
 If resistance is less than 1 , electrical continuity is good.
 If resistance is more than 1 , contact INFICON (refer to section 1.3 on
page 1-2 .)