Skip to main content

Off After Low Emission vacuum error on the AutoSpec - WKB55829

Article number: 55829


  • Ion gauge "Off After Low Emission" error message appears in Tune Status and Vacuum Control page
  • Cannot switch on the ion gauge; no vacuum reading is possible


  • AutoSpec Ultima
  • AutoSpec Premier


The ion gauge filament is open circuit and/or is shorting to ground.


  1. Check the resistance of your meter leads before making any measurement; touch the black and red measurement leads together.
    • The resistance reading should be very low—optimally, less than one Ohm.
  2. Measure the resistance between pins 7 and 8 on the ion gauge end flange.
    • AutoSpec_Ion_Gauge_Connection_Flange_External.jpg
  3. Expect to see a resistance less than 1 Ohm, take into account the resistance of the meter leads as above. This would show the filament is good.
  4. If the resistance is very high/infinite or open circuit, the filament has failed and must be replaced.
    • Part number for the Ion Gauge Filament: 7991802 - IR23 FILAMENT (VIG 8)
    • Part number for the complete Ion Gauge Assy:  6060920 - GAUGE ION VIG 8 KF40
  5. If the resistance is good (less than 1 Ohm), suspect a grounded internal filament (short circuit).
  6. Measure the resistance from either pin 7 or pin 8 to the instrument housing/ground.
  7. Expect to see a high, open-circuit resistance. This is the normal condition.
  8. A low resistance indicates a short circuit, which needs to be rectified.
  9. The ion gauge must be removed following all vacuum handling procedures, and the short must be cleared by carefully adjusting the filament.
    • NOTE: Never touch the ion gauge filament with bare hands. The filament is thorium-coated and mildly radioactive.
    • It is possible that no resistance will be seen when you make the measurement to ground. The filament may be in close proximity to the instrument housing, making a real connection only when voltage and current are supplied.
    • If the Analyzer region shows the error, test both ion gauges for a short to ground.
    • Disconnect the Analyzer 2 ion gauge connector (BB350), and try to turn on the Analyzer 1 ion gauge. If a reading is seen, the problem is in the Analyzer 2 ion gauge.
    • Likewise, disconnect the Analyzer 1 ion gauge connector (BB150), and try to turn on the Analyzer 2 ion gauge. If a reading is seen, the problem is in the Analyzer 1 ion gauge. 


See article WKB96022 on how an ion gauge works.

Not able to find a solution? Click here to request help.