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Thermo Fisher Scientific

FEG cannot stay on in vacuum ready mode


FEG cannot stay power on as long as the vacuum is in ready mode


Themis 300 G2


These are possible resolutions for the issue:

  • Adjusted Vcp microswitch fixed the issue


These are possible causes for the issue:

  • 24V Mains interlock was activated


  1. FEG is not able to stay power on when vacuum is in ready mode. Feg can stay power on if vacuum is manual mode. As long as the system is evacuating, then it will turn off both FEG and HT. This issue started to happen after normal operation.
  2. When vacuum is on, HIB/HAB has error LEDs. See attached picture.
  3. When vacuum is on, 24V filament power supply will not flash
  4. Measured interlocks: Column separation 4.7V, SF6 24V, HT Tank 15V
  5. When vacuum is on, interlock HIB/HAB test will fail, see attached picture
  6. HIB/HAB/24V power supply was exchanged and it did not fix the issue
  7. Followed 105847 and checked FSB, X5-1=0V, and X5-7 =12V, X5-3 =12V, replaced FSB per the instruction and still it did not fix the issue
  8. Measure 24V Mains interlock, found X58-2 and X59-1/X59-2 is missing
  9. Adjusted Vcp microswitch and fixed the issue

clipboard_e51c4d1849f755cd3daee3f80f4339685.png clipboard_ee7a332bb17faf98b1c9f2ac80d0e58c0.png



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