Maintenance
When driving in conditions with rain, snow, mud or dirt and dust, the windscreen and the protective filters will
protect the diaphragm. This also means, of course, that over time they will become contaminated. The only way
to deal with this problem is visual inspection routines that take the driving conditions into account.
Apart from the obvious visual signs of contamination you should look for water in the windscreen. Especially in
cold weather near or below freezing temperatures, water may accumulate and freeze to ice in the windscreen.
Has this happened, the windscreen should probably be discarded.
If a protection grid is clogged with dirt and dust, it should be replaced.
Also beware that if there is water inside the 1/2” grid, and this water freezes, this will most probably damage the
diaphragm, therefore wet items must be dried between test sessions.
Recommended Inspection and service routines
Temperature below 0
º
C/32
º
F
Temperature above 0
º
C/32
º
F
Dry roads, low humidity
Wet roads, high humidity
Dry roads, low humidity
Wet roads, high humidity
Calibration intervals
Once a week
Daily
Once a week
Daily
Inspection intervals
Once a week
Daily
Once a week
Daily
Windscreen
Check and clean* for dust
Exchange daily
Check and clean* for dust
Exchange daily
1” Grid (filter)
Check and clean* for dust Check for contamination,
clean*, dry or exchange
Check and clean* for dust
Check for contamination,
clean*, dry or exchange
1/2” Grid (filter)
Check and clean* for dust Check for contamination,
clean*, dry or exchange
Check and clean* for dust
Check for contamination,
clean*, dry or exchange
*Cleaning: compressed air applied from the inside.
Calibration
The microphone set is factory calibrated with the 1/2” protection grid mounted. We therefore recommend that
you dismount the 1” protection grid prior to calibration. In this way you can directly compare your calibration
result with the factory calibration.
We recommend using a 42AG Multifunction Sound Calibrator with an RA0341
Calibration Adapter.
Warranty and Service
All parts are manufactured and assembled in Denmark by skilled and dedicated operators in a verified clean-
room environment. Our warranty against defective materials and workmanship is 5 years, the windscreen and
the protective grids are consumables covered by a 6 month warranty.
The warranty does not cover damages to the protection grids caused by their intended use in the challenging
conditions in the wheelhouse.
GRAS offers a complete overhaul including calibration at a reasonable price.
LI0242 – 27 March 2019
