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Leica S430 Scanning Electron Microscope (view source)
Revision as of 02:02, 8 April 2014
, 02:02, 8 April 2014no edit summary
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== Troubleshooting ==
=== Final Vacuum ===
Final vacuum doesn't want to drop beyond 1.8e-5 torr. However, after leaving the scope on, the vacuum increases to around 1.3e-4 torr. Venting and pumping the chamber always fixes the problem. Also, when pumping down, the pressure bounces around a bit initially, and then suddenly drops from 1.0e-4 to 6e-5 torr within a second, which is likely a physical impossibility. Possibilities:
* The Penning vacuum gauge can become plated with ions. This is a very common failure mode and can cause false readings. Lightly sanding the anode and cathode, and washing everything in acetone, is the manufacturer's recommended cleaning procedure. This probably hasn't been done in a very long time and is a good first step before further troubleshooting. For all we know, we don't have a problem. Lending support to this is an absence of image degradation between the 1.3e-4 "bad" state and the 3e-5 "good" state after venting and pumping.
* The vent solenoid has been known to leak on other SEM users' scopes.
* Chamber and gun gaskets should be greased with a suitable high vacuum grease, e.g. Apiezon M.
* Rotation speed on the turbomolecular pump can be checked, which correlates to chamber pressure.
=== Image Processor board loses communications ===
We have observed after moving the scope to its new location that the vacuum spontaneously shuts off. Error messages pop up on the console several seconds later concerning timeouts to the Stage and Vacuum board.
Communications between boards happens via RS232 over fiber optic cables. The Opto 10 and 11 connectors handle communication to the Stage and Vacuum board, and unfortunately it appears tension was applied to the fiber, causing damage to the connector on the image processor board. The cable isn't locking in place properly.
On a single occasion, communication to the EHT board was lost. This corresponds to Opto 8 and 9.
A dual cable plugs into a single port, Opto 1, for the HRRU pixel data. The fiber connector for this has snapped. This is not critical as we are not using the HRRU.
Repair is be possible. The connector in question is a "hp 9534 R-2521" with a T-2521 next to it. These appear commonly available, but soldering to the image processor board should be considered a last resort.
== Maintenance Log ==
== Maintenance Log ==