Varian Turbo-V 301 system fault. S1: Overtime

I have a Varian Turbo-V 301 pump paired with a model 969-9537 controller and it does not come up to speed, eventually displaying S1: Overtime fault.

From a soft start, during the first step, the turbo spins up to a displayed 12 KRPM with a current of 1.3 A, (P=24 W). The spin rate then slows (6-10 KRPM), though current has increased to ~1.6 A (P=33 W), which I understand to be the limit for maximum allowable power (from page 82 of manual 87-900-940-01 (F)).

I recognise that this type of symptom would typically point to a leak, however for this setup is unlikely, and the foreline is maintained in the low to mid 10-3 mbar range throughout (low while turbo is off, mid while it's trying to spin up).

Could this be a known failure mode for this controller? Is there any troubleshooting I can do in the absence of a spare controller?
I would love to hear other opinions or suggestions.

Many thanks!

  • Your controller is going in Auto Tune

    Autotuning condition is shown when the controller has delivered an output power level higher than a typical value, but the pump is still not reaching full speed value.

    It does not matter if it is a normal start, soft start or low speed.


    Possible reasons for AUTOTUNING.

    • Pump is unable to reach full speed because of:
      • High gas load (AUTOTUNING will become TOO HIGH LOAD error if the auto tuning condition is not restored (usually 15 mins))
        • System leak
        • Bad or insufficient foreline pressure
        • Turbo Pump mechanical issue (bearing worn out or rotor damaged or mechanical contact)


    • Check the pumping system for leaks
    • Check the foreline pressure/ Foreline pump
    • Remove the turbo pump from the system and check to see if the rotor spins freely by hand (carefully - wearing gloves)

    If the rotor doesn’t free spin very easily (or is visibly damaged) it is a mechanical failure of the pump.

    I've included 2 Turbo/controller Troubleshooting guides for your reference.

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