5-4
5.2.1 Vacuum Related Problems
Vacuum Failure - The chamber cannot hold a vacuum or cannot reach vacuum
level specification.
Typical Causes:
• Leaking O-ring seals: O-rings are used to seal the lid, electrodes,
thermocouple, sight glass and view-port cooling sleeve. These items can
be found on the appropriate pictorial drawings in the Illustrated Parts
Manual. Refer to Section 5.4.
Referring to the pictorial drawing “Chamber Assembly,” locate item 26.
Item 26 is the electrode seal.
Referring to the pictorial drawing “Thermocouple Installation,” locate
Item 2, this is the thermocouple O-ring.
Referring to the pictorial drawing, “Lid Assembly,” locate items 8, 10,
and 12. Item 8 O-ring is for the sight glass, item 10 is for the cooling
sleeve, and item 12 is the lid O-ring seal.
• Defective solenoid valves: Please refer to the plumbing diagram in
Section 6 and locate 1BSOL and 2BSOL. These valves are designed for
vacuum service and are used to isolate the chamber from the gas supply;
if either is defective the chamber will leak. 3SOL is isolated from the
chamber by check valve 3CV and cannot affect vacuum performance.
4SOL is used to isolate the vacuum pump from the system and remains
open when the pump is evacuating the system.
The gas distribution system as shown on the plumbing diagram is
pictorially divided into three circuits to make it easier to troubleshoot and
to locate components. 1BSOL and 2BSOL can be found on the pictorial
drawing “GAS 1 & GAS 2 Circuit.” 3SOL can be found on pictorial
drawing “Exhaust Circuit,” and 4SOL can be found on pictorial drawing
“Vacuum Circuit.”
• Defective check valve: Please refer to the plumbing diagram and locate
3CV check valve. This component is item 4 on pictorial drawing
“Exhaust Circuit.” If it is determined that this part is defective it must be
replaced.
• Leaking or defective fittings: These are common failures but can be very
difficult to find without leak detection equipment. Inexpensive bubble
forming leak detectors can be used to locate gross leaks by pressurizing
suspected areas and looking for bubbles; these soap solutions however
are not capable of finding small leaks that typically affect vacuum
performance.
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