6
Service & Maintenance
39
Series 943 Cold Cathode Vacuum Sensor
Instruction Manual - #100009887
6.5.1 Disassembly
Tools required: clean tweezers and smooth-jaw, needle-nose pliers. Wear cleanroom gloves during
all handling and cleaning procedure.
See Section 6-1 for disassembly and cleaning, and Section 6-2 for final reassembly.
3.
Loosen the thumb screw on top of the sensor cable and then remove it. Loosen the two flat
head screws (15). Remove the magnet (14).
4.
Using the smooth-jaw, needle-nose pliers, firmly grab the compression spring (1) at the tip
closest to the flange.
5.
Pull on the compression spring while rotating it to free it from the formed groove of the sensor
body (7). Continue to pull until the compression spring is completely free.
6.
Carefully remove the remaining components from the sensor body.
6.5.2 Cleaning the Components
1.
If ultrasonic cleaning, use high quality detergents compatible with aluminum, such as
ALCONOX
®
.
2.
Scrubbing with mild abrasives can remove most contamination.
3.
Scotch-Brite™ or a fine emery cloth may be effective. Rinse with alcohol.
4.
Clean aluminum and ceramic parts chemically in a wash, such as a 5 to
5.
20% sodium hydroxide solution (not for semiconductor processing), at room temperature
(20 °C) for one minute. Follow with a preliminary rinse of deionized water. Remove the black
residue left on aluminum parts due to this process in a 50% to 70% nitric acid dip for about
5 minutes.
6.
Each of the above cleaning methods should be followed with multiple rinses of deionized
water. Dry all internal components and the sensor body (7) in a clean oven. The two ceramic
spacers, (2) and (5), are slightly porous and will require longer drying time in the oven to drive
off the absorbed water.
Delicate Internal Components
Do not bend the anode (8) or the leaf spring (9) on the ion
current feed through pin (13) when disassembling or
assembling the Sensor; they are very fragile and could break.
Delicate Internal Components
Do not use chemicals to clean the anode (8); mild abrasives or
ultrasonic cleaning are acceptable.
