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Warranty and Maintenance
The 90CA is assembled and tested by G.R.A.S. before leaving the factory. An individual
test certificate is included with each 90CA.
Warranty
All G.R.A.S. products are made of high-quality materials that will ensure life-long stabil-
ity and robustness. The 90CA is delivered with a 2-year warranty.
Damaged diaphragms in microphones can be replaced.
The warranty does not cover products that are damaged due to negligent use, an incor-
rect power supply, or an incorrect connection to the equipment.
Calibration
Before leaving the factory, all G.R.A.S. products are calibrated in a controlled laboratory
environment using traceable calibration equipment. We recommend a yearly recalibration
at minimum, depending on the use, measurement environment, and internal quality
control programs.
We recommend a daily check of the 90CA using the 40AG reference microphone to
ensure the validity of your calibrations. If you start each calibration session with a level
measurement of the 40AG you can verify that the system works properly.
Cleaning
Keep the system in a clean environment; keep the reference pistonphone and micro-
phone in a safe and dry place when not in use.
Store the preamplifiers in a clean and dust-free environment.
Cover the terminal areas with their protection caps to prevent dust and tiny hairs from
entering the high-impedant connector area.
Grids and windscreens make an adequate protection, reducing any need to clean
microphones.
Avoid touching the diaphragm on any microphone during general use. Never touch the
surface with anything that has a point such as a pencil or finger.
If something is spilled on the diaphragm, such as oil, use a clean cloth or cotton ball
dipped in alcohol or benzine (for oils) to wipe the surface, using even pressure at all
times. Use cleaning solutions that are appropriate, for example, benzine, alcohol, and so
on.