Ulvac CRYOPUMP CRYO-U Series Instruction Manual page 79

Troubleshooting
Problem
Ⅰ．
It takes too long to
rough pump the
cryopump.
Or, the pressure
buildup speed from
40Pa is greater than
1.3Pa/min.
Ⅱ．
Neither the compressor
unit nor the cryopump
start.
Ⅲ．
A compressor unit
starts, but a cryopump
doesn't start. Or the
cryopump is stopped,
but the compressor
unit is running
continuously.
A-2
Table A-1 Cryopump Fault Diagnosis
Possible cause
1) A leakage through a pressure relief
valve.
2) A large amount of gas with low
vapor pressure, such as water is
adsorbed on the charcoal of 15K
cryopanel (2).
3) Inner kit is contaminated with oil or
deposition material.
4) There is a leakage in the
cryopump or the vacuum system.
Consult the instruction manual of compressor unit for details.
1) A refrigerator power cable is not
connected to the refrigerator unit.
2) In case of multi-operation of the
refrigerator unit, ON/OFF state of
the refrigerator is decided with the
control signal of the system that a
user prepares. Therefore, check
your control method to judge
whether the halt condition of the
refrigerator is normal or not.
ULVAC CRYOGENICS INCORPORATED
Corrective action
Remove a cap of the pressure relief
valve rotating in
direction. Clean the O-ring and O-
ring sheet.
Confirm the safety of the gas which
may blow off from the pump before
removing the pressure relief valve.
Do not block the pressure relief
valve.
Introduce dry nitrogen or argon into
the cryopump and repeat rough
pumping.
Clean the inner kit or replace it with
a new one.
Find and stop the leak.
Turn off the compressor unit and
connect the refrigerator power cable
to the refrigerator unit.
CAUTION
Do not connect the refrigerator
power cable to the refrigerator unit
without turning off the compressor
unit. The refrigerator motor may be
damaged if this caution is not
followed.
anticlockwise
WARNING