>Dear list members:
>We have a Micromass Optima with Isochrome continueous flow interface here at
>Iowa State University. Recently we are having a vacuum problem. When CRT7
>valve is closed, the vacuum reading is only 3.6E-6 (normally it is
>about 1E-8 mbar). This happened gradually. If we reopened and then closed the
>valve, we can occasionally get a vacuum of 1E-7mbar. But now we can only get
>3.6E-6mbar no matter the CRT7 valve is closed or not. We changed a new
>copper pad seal, a new knife edge and a new wavy washer, the vacuum is still
>3.6E-6mbar. We degassed ion gauge, the reading is still same. When we tried to
>degas the ion gauge again, the computer gave us message, it reads "ion gauge
>1 bad calibration data" and no vacuum reading in ion gauge display. I
>rebooted the computer but everytime when I try to turn the ion gauge on, I
>gets the same message. Any suggestions regarding to these two problems will
>be greatly appreciated.

This may sound stupid, but have you checked to make sure the guage is giving
proper readings?  One of the two vacuume guages on our Europa 20/20 analyzer
went out and started giving readings in the range you describe even though
background scans of the closed-off system showed normal readings (i.e. very
low amounts of anything in the system).  Luckly, the guage "fixed" itself over
time.  I guess it was just dirty.  Sorry, but I have no idea about the second
problem.  Good luck.

Myq

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