Troubleshooting
4-2
P/N 8040613
C
HELIX TECHNOLOGY CORPORATION
-
TI
CRYOGENICS
Table 4-1: Troubleshooting Procedures
Problem
Possible Cause
Corrective Action
High base pressure of vacuum
system, and a cryopump tem-
perature below 20K.
Air-to-vacuum leak in vac-
uum system or in cryopump.
Check cryopump relief valve
for proper seating.
Check cryopump for leaks.
Check vacuum chamber and
Hi-Vac valve for leaks.
High partial pressure of non-
condensables (helium,
hydrogen, or neon) within
the cryopump because the
15K array has reached full
capacity.
Regenerate the cryopump as
described in Section 3 -
Regeneration.
One of the arrays is loose,
which is preventing good
thermal contact with the cold
station.
Warm the cryopump to ambi-
ent temperature and retighten
the array mounting screws to
15 - 20 in. lbs.
High base pressure of vacuum
system, and a cryopump tem-
perature above 20K.
Decrease in cryopump cold
head performance.
If the helium return pressure
gauge reads below the nor-
mal-operating return pres-
sure 60-85 psig (415-590
kPa), add gas as described in
the appropriate Compressor
manual.
High partial pressure of non-
condensables (helium,
hydrogen, or neon) within
the cryopump because the
15K array has reached full
capacity.
Regenerate the cryopump as
described in Section 3 -
Regeneration.
Excessive thermal load on
frontal array.
Reduce the thermal radiation
load by 1) shielding the cry-
opump or 2) lowering the
temperature of the radiating
surface.
