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Page 22 of 26
Probe Maintenance - ensuring low-noise performance
The EmD sensor sets up has a high-voltage electric field in the space
behind the diaphragm. Diaphragm movement modulates this field, such
that extremely small vibrations of the diaphragm are directly detected
as field changes. For proper operation, the space in which the field
exists must be clean and dust- and lint-free, and not contain excess
moisture.
Under normal circumstances, the field will remain clean, and require no
maintenance. However, if dust, lint or moisture do enter the Probe,
unexpected background or louder noises can occur. The simple cleaning
procedures below can then be used to rapidly re-establish noise-free
operation, using a standard alcohol swab. These procedures are
described in great detail for clarity. However, they are simple, and
take less than 2 minutes to complete.
Noise Symptoms
Dust, lint or moisture in the field produces the following possible symptoms:
- intermittent faint white-noise.
- squealing sounds, either faint or more prominent.
- ticking sounds (static discharges).
- above artifact sounds change when the diaphragm is pressed or unscrewed slightly.
If you notice any of these symptoms, follow the cleaning procedures
below. If your ds32a is operating well, these procedures are not
required for regular maintenance.
 Alcohol Cleaning
- Make sure the unit is turned off.
- Unscrew the diaphragm as described above. Open the
probe in a clean, dust-free environment, and place the open part of the
probe face-up. DO not touch the brass plate. Do not place the open
probe on a dusty surface or a cloth surface. Lint could be attracted
into the Probe.
- Using the alcohol swab, carefully wipe the brass plate inside the
Probe. Do not touch the brass plate. This could permanently damage the
sensor.
- Using a lint-free alcohol swab, carefully wipe the inner surface
of the diaphragm as shown. Do not touch the inner plastic surface of
the diaphragm with anything other than the alcohol swab.
- Allow the diaphragm and probe surfaces to dry by evaporation. Do not
close the unit and power it up with alcohol moisture on the diaphragm.
Only after evaporation will the surfaces be clean and ready for use.
Air Drying and Cleaning
The probe can further be cleaned using a dry air aerosol spray. These
are available at hardware or office supply store, and are usually used
for cleaning computers. This cleaning method is useful when the unit
has been exposed to extreme dust, lint, humidity or moisture, or in
addition to the alcohol-swab cleaning described above, the rare
instance than contaminants exist inside the probe.
- Make sure the unit is turned off.
- Rotate the Aperture Ring to the open position to allow air flow in the Probe.
- Unscrew the Diaphragm Ring and remove the diaphragm. Place the
diaphragm with Thinklabs logo face DOWN, so the inside surface does not
become dusty.
- Using the dry air spray with the spray’s plastic straw, spray the
inside of the probe via the vent holes in the Aperture Ring, and around
the circumference of the brass plate. Do not touch the brass plate with
anything, including the plastic straw. Do not overspray. White
condensation sometimes forms, which is counterproductive when trying to
dry out the Probe.
- Replace the Diaphragm, and close the Aperture Ring. Wait a few
minutes for the Probe to stabilize, and then power up the unit to test.
If these cleaning procedures do not correct the problem, see Tips and
Troubleshooting and contact Thinklabs. We can assist you and
ensure that your ds32a is operating optimally.
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