INFICON SQM-242 Thin Film Deposition Controller Card Operating Manual - Manual (Page 56)

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SQM-242 Operating Manual
7.1.1 Troubleshooting the SQM-242
Table 7-1 General Troubleshooting
SYMPTOM CAUSE REMEDY
1. Crystal fail message is
always on. a. Sensor not connected. a. Verify proper sensor
connections.
b. SQM-242 malfunctioning. b. If available, insert a known
working SQM-242, or other
QCM, in place of suspect
one; if SQM-242 is confirmed
bad, contact INFICON
service department.
c. Defective cable from
feedthrough to oscillator. c. Use an Ohm meter or
DMM to check electrical
continuity or isolation as
appropriate.
d. Poor electrical contact in
the sensor, feedthroughs, or
in-vacuum cable. d. Use an Ohm meter or
DMM to check electrical
continuity or isolation as
appropriate.
e. Failed crystal/no
crystal/defective crystal. e. Replace crystal with a new
INFICON crystal.
f. Two crystals placed into the
crystal holder. f. Remove one of the
crystals.
g. Frequency of crystal out of
range. g. Verify that the crystal
frequency is within the
required range, use
INFICON crystals. Set the
desired range in the
software.
2. Noisy signal. a. Distance from sensor head
to the oscillator is longer than
40 in. (101.6 cm). a. Replace cables to
preserve the maximum
allowable length.
b. Mechanical/electric noise
sources located near the
SQM-242/cables. b. Reroute cables to reduce
noise pickup (1 ft away from
high power conducting lines
makes a sizable reduction in
the amount of noise), keep all
ground wires short with large
surface area to minimize
ground impedance.