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Cygnus 2 Operating Manual
13.8.1.2 Feedthrough Or In-Vacuum Cable
Diagnostic Procedure
1 Refer to Figure 13-8 on page 13-26. Remove the in-vacuum cable from the
Sensor Head at point B.
2 Connect the Crystal Sensor Emulator to the in-vacuum cable.
If the Crystal Fail message disappears after approximately five seconds,
the feedthrough and in-vacuum cable are working properly. Re-install the
in-vacuum cable to the Sensor Head. Go to section section 13.8.1.3 on
page 13-29.
If the Crystal Fail message remains, continue at step 3.
3 Disconnect the in-vacuum cable from the feedthrough and the Emulator.
Disconnect the six-inch BNC cable from the feedthrough.
4 Using an Ohm Meter, verify electrical continuity from the BNC center pin on the
feedthrough to the Microdot center pin on the feedthrough. A typical value
would be less than 0.2 ohms.
5 Verify electrical isolation of the center pin on the feedthrough from the electrical
ground (feedthrough body). A typical value would be in excess of 10 megohms.
If the feedthrough is found to be defective, replace the feedthrough, re-attach the
BNC and in-vacuum cables, and repeat this procedure starting at Step 2, otherwise
continue at step 6.
6 Verify electrical continuity from center pin to center pin on the in-vacuum cable.
7 Verify that the center pin of the in-vacuum cable is electrically isolated from the
in-vacuum cable shield.
If the in-vacuum cable is found to be defective, replace the in-vacuum cable.
Re-attach the BNC and in-vacuum cables, and repeat this procedure starting at
Step 2, otherwise continue at step 8.
8 Connect the in-vacuum cable to the feedthrough.
9 Verify electrical continuity from the center pin on the BNC connector of the
feedthrough to the center pin on the un-terminated end of the in-vacuum cable.
10 Verify electrical isolation from the center pin to electrical ground (feedthrough
body).
If the feedthrough/in-vacuum cable system is found to be defective, look for
defective electrical contacts at the feedthrough to in-vacuum cable connection.
Repair or replace the feedthrough as necessary. Re-attach the BNC and in-vacuum
cables and repeat this procedure starting at step 2. Otherwise, continue at step 11.
11 Connect the six-inch BNC cable to the feedthrough and disconnect it from the
Crystal Interface Unit (or Oscillator)
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