Guralp Systems CMG-3T - Manual (Page 31)

Operator's guide
out, the instrument is ready for transportation.
•
To re-centre the sensor masses, hold down the ENABLE and
CENTRE buttons simultaneously for 7 seconds. When the BUSY
LED stops flashing, the centring process has finished. You may
need to initiate several rounds of centring before the instrument
is ready; when no more centring is required, pressing the
ENABLE and CENTRE buttons has no effect.
For more details on the control system, see Section 5.2, page 36.
The standard breakout box is rain resistant but not waterproof. If you
intend to use a breakout box in your installation, you should site it
away from potential flooding. If this is not possible, a larger unit is
optionally available which can be immersed in water. (The 3T itself is,
however, completely waterproof.)
4.2 The hand-held control unit
This portable control unit provides
easy access to the seismometer's
control commands, as well as
displaying the output velocity and
mass position (i.e. acceleration) on
an analogue meter. It takes input
from the 26-pin connector at the
bottom, and repeats it at the
connector on the side for
connection to further equipment.
The hand-held control unit can be
sited up to fifty metres from the
breakout box.
The meter
The meter at the top of the unit allows you to monitor the voltage
outputs of the instrument. You can use the knob below to select, for
each of the three components, either the mass position output or the
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