We lost the objective lens on our 8200 some time back. The scope would no longer focus at all. I don't think there were problems with the current, per se. A replacement lens coil took care of the problem. 

After that, JEOL came around retrofitting scopes with sensors to verify coolant flow and measuring lens temperature. 

Warren Straszheim

-----Original Message-----
From: JEOL-Focused Probe Users List [mailto:[log in to unmask]] On Behalf Of Andrea Orlando
Sent: Friday, October 16, 2015 2:31 AM
To: [log in to unmask]
Subject: [PROBEUSERS] oil of objective lens and no beam

Dear microanalysts,
our Jxa-8600 electron microprobe automatically switched off its electronic due to a failure in a cooling of objective lens. We checked oil in the apposite reservoir and we refilled it since its level was about 4-5 cm from the top. We re-started the probe, the failure error disappeared, the electronic switched on but proceeding as usual to saturate the filament  we realized that current is extremely variable and high (up to 450 nA on Farday cup), we have no images on CRT video and we can not observe beam in the optical video. We inspected the instrument and not apparent oil leakage can be observed in both electron column ans sample chamber. 
Any suggestions?
Thanks in advance.
Andrea

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