Ametek Dycor Dymaxion Mass Spectrometer, User Manual

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Maintenance & Troubleshooting
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6-9
Closed/Enclosed Source
• Remove the filament (see instructions in this chapter).
• Loosen the set screws on the barrel connectors that hold the three
leads coming down from the source elements. The filament bases can
be left intact. Remove the source assembly from the mass filter.
1.
Loosen and remove the three (3) locknuts that hold the source con-
nection rods in place on the lenses. Refer to Figure 6-4.
2.
Loosen and remove the three (3) screws that hold the lens together
in sandwich form. Be careful not to lose the small ceramic or metal
washers from the source; each serves to hold the source in precise
alignment.
Cleaning
Closed/Enclosed Source
The conductance limited/enclosed source can be fully disassembled and
cleansed of deposits. However, only the removable ion volume will usually
need cleaning since this is where most sample ionization occurs.
NOTE

We recommend that you send the source back to the factory if it needs
cleaning. You should not attempt to clean the source yourself unless you are
familiar with disassembling and reassembling the source and replacing the
filament.
The source cannot be disassembled without damaging the filament.
Be prepared to install a new filament if you disassemble the source for
cleaning or any other purpose.
Mass filter
Deposits can form at the entrance to the mass filter rods when they are oper-
ated at high pressures or over a long period of time.
•
Deposits can sometimes be seen as discolorations on the metal. In
some atmospheres, the rods might be coated with an invisible layer
that will keep the mass filter from operating properly. This will result
in a loss of sensitivity over the full range of the spectrum. If the peaks
disappear at high scan speeds, an insulating layer may have devel-
oped on the surface of the rods.
•
Unless the nature of these discolorations can be identified exactly, the
only sure way of removing them is with a fine abrasive.
•
The entire quadrupole head assembly must be disassembled to clean
the rods.
NOTE

We recommend that the assembly be returned to the factory where the rods
can be cleaned properly.