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QTof Tof Vacuum out of range Part 1 - WKB3168

Article number: 3168


  • The Tof penning gauge reads 1e-8 mBarr, which is an erroneous reading
  • There is an error message in the MS console or at the bottom of the tune page that reads 'Tof vacuum out of range'


  • Q-Tof
  • MassLynx
  • Tof


The penning gauge is shorted and not reading the actual vacuum. The short is usually from some sort of debris in the penning gauge.


  1. Remove the panels to see the Tof Penning Gauge. Leave it attached to the instrument as the pumps are still on.
  2. Disconnect the rj45 cable going to the penning gauge (this can be done with the electronics on).
  3. Rotate the orange or grey magnetic housing anti-clockwise, and pull it off.
  4. Take a sizable metal wrench and knock on the side of the metal penning gauge body to dislodge the short, but not the penning gauge body.
  5. Re-assemble the penning gauge (housing and cable).
  6. Check for a Tof vacuum reading on the tune page. It should read e-6 or e-7 mBar.
  7. Put the panels back on.


If this did not work, see KB article - QTof Tof Vacuum out of range Part 2.

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