Vacuum Fail on 5977B MSD

I have a 5977B MSD that is experiencing a vacuum failure after a scheduled shutdown for renovation work in our facility. Work was completed and now we are restarting the system. At first we though it was the roughing pump, but we have bypassed the remote start and plugged it directly into an outlet. Here's our order of operations:

1. plug in roughing pump and let this run for 30 minutes to achieve a good vacuum, turbo blades are spinning at ~40% although the turbo is not turned on yet. There is no leak on this roughing pump.

2. turn ON the GC, MSD and computer, wait for boot to complete

3. start Mass Hunter, go to vacuum control and start the pump down. Please note at this point our turbo is already spinning well due to the roughing pump vacuum (see point 1).

4. turbo is spinning faster, we see it climb to ~ 72 % then the turbo fails, we hear a "click" at the back of the instrument, and the pump speed slows down.

5. message on the LCD of the GC reads: "MS State: Vacuum Fail. HiVac Gauge is OFF"

What to do? Suggestions are most welcome. 

  • If the turbo blades are spinning from the rough pump -- there must be air flowing past them for them to move.   If you do this on a system that was already at vacuum, the turbo blades barely spin.

    I hate to ask simple questions but:

    Is there a column installed with the proper nut and ferrule?
    Is the calibration valve closed?
    Are you holding the analyzer door shut?

    Can you hear any unusual sucking noises?

    If the turbo does not spin past 80% in about 7 minutes, the system will shut itself down for protection.

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