Chromatography Forum

We have an HP5890/5970 GC/MS that was working fine until yesterday when the unit lost vacuum. It was operating at a vacuum of 10-5 and now it will only go to 10-3. I have shut down the instrument and restarted it with no change. I also blocked off the MS inlet to eliminate the GC end. One other thing I noticed was that the power switches for the turbo pump and the heater on the front panel of the 5970 do not light up when they are flipped on. They used to when the instrument was working. Could it be the turbo pump failing? Any other insights? Thanks in advance for advice.

10-3 your turbo is not working. That pressure is from the rough pump.
Check for blown fuses, loose connections etc.

Bigbear,

Thanks for the reply. It turned out to be the turbomolecular pump. When I removed the oil wick holder and the felt disk from the bottom of the pump, the bearings fell out. They were toast. A replacement pump is on order.