INFICON IQM-233 Thin Film Deposition Controller PCI-Express Card Operating Manual - Manual (Page 76)

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IQM-233 Operating Manual
Table 5-1 Symptom/Cause/Remedy Chart
SYMPTOM CAUSE REMEDY
Freq (Hz) displays unstable
or drifting frequency. Temperature of the crystal is
unstable (an AT-cut crystal
may drift as much as
10 Hz/°C). Control the vacuum chamber
temperature.
Move the crystal farther away
from the source (at least
25.4 cm (10 in.) from source).
Check sensor water cooling
for correct flow and
temperature.
Clean or replace the crystal
holder.
Use SPC-1157-G10 thermal
shock crystals designed to
minimize frequency shifts
due to heat load.
Humidity level on the crystal
is changing. Moisture being
absorbed or exuded from the
crystal surface. Avoid condensation by
turning off cooling water to
sensor before opening the
vacuum chamber to air, and
then flow heated water above
the room’s dew point through
the sensor when the
chamber is open.
Defective in-vacuum cable or
coax cables. Use an ohmmeter to check
electrical continuity and
isolation.
Check crystal and crystal
holder’s crystal seating
surface for scratches or
contamination. Replace crystal.
Clean or replace crystal
holder.
Freq (Hz) displays unstable
and incorrect frequency. Excessive cable length
between oscillator and
crystal causes a
self-oscillation condition. Use no longer than a 78.1 cm
(30.75 in.) in-vacuum cable.
Use only the 15.2 cm (6 in.)
cable between oscillator and
feedthrough.