by
tima » Thu Jun 24, 2010 9:11 pm
You may have a leak...sometimes the turbo pump can't get up to speed when there is a sizable leak. Listen to your rough pump and if there is a big leak then you will hear a "gurgling" sound.
Another, unthinkable event could be the bearings on the turbo pump are starting to fail. We had a Varian 2000 and every year we had to change the turbo pump (very expensive) because there was a leak in the manifold coming from the rough pump. Very difficult to find and only after 4 turbo pump failures did the service engineer find it.
Vent the MS, remove the turbo pump and see if the bearing are free wheeling. This is easy to check once the pump is in your hands. Just hold it up right and then quickely twist the pump in your hand and watch the turbo vains move as you twist the pump. If it moves freely then bearings should be OK. Whenever, I had a problem as you describe, we had to buy a new pump.
You can get them refurbish but your are looking at about $5000.
Timothy