FRS 8166

Filament #1 on the Pfeiffer RGA seems to be burned out. It turns off a second after turning it on. I switched to filament #2. It would not stay on either. The default emission current was set to 2 mA. I lowered it to 0.1 mA. The 
filament (#2) stayed on at that value. Then I raised to 0.3 mA (you have to 
click in a different window to activate the new setting btw). Then I 
raised to 1 mA where the filament automatically turned off. Went back to 
0.3 mA and that's where it's sitting for now. Pfeiffer suggested we let it 
warm up and slowly ramp up to 2 mA. These steps are sometimes needed when the filament hasn't been used for a long time (not the case here). Something else is going on.

The error message we were getting from the filament turning off was 
"emission error" or E002. Pfeiffer said a burned out filament will usually 
yield a different type of error, but sometimes these fail such that the 
filament still registers a current - when the broken filament cools it 
reconnects. Here is a manual describing emission error:

ftp://ftp.aerodyne.com/ACSM/ACSM_Pack/Quadara2/Manuals/English/QUADERA/quadera.pdf

We verified the RGA turbo is ON and pumping out the RGA volume. One theory is that during the bake of the RGA (during oven load bake) we sprung an air leak and now the turbo can't keep up with the leak rate which is causing a high head pressure - too high for a filament to tolerate. Note that one of the two turbos on VBOC is at 33C, which is a little high (two fans are blowing on it). The other is at 27C. Also, the foreline pressure is reading 0.018 Torr. Normally at 0.016 or 0.017 Torr. We should add HV pressure gauges to the system for times like this.

Also, one of the electronics units has a recessed pin socket. The other 
two spare units yielded the same error (filament turning off almost 
immediately). Maybe instead of replacing the SRS with Pfeiffer we should 
replace the Pfeiffer with SRS because of these pin issues due the frequency of removing and reinstalling the electronics in between bakes.