Guralp Systems CMG-3TB - Manual (Page 29)

Operator's guide
7. Fix the signal cable to the main lifting cable about 1 m above the
strain relief mechanism using a metal clamp (a nylon cable tie
may be sufficient for shallow installations.) Leave a little slack
in the signal cable between the clamp and the strain relief
mechanism.
8. Position the assembly over the top of the borehole. Do not allow
it to drag across the ground.
9. Lower the sonde so that its base is just level with the borehole
mouth. If there is a depth gauge on the winch, set this to zero.
10.Continue to lower the sonde to a depth of about 1 m, so that the
instrument is still visible.
11.Extend the hole lock arm (see Section 2.6, page 22) to check
that it fits your borehole. The current drawn should dip slightly
as the arm touches the casing, then drop to zero when it is fully
extended. Check that the sonde is firmly anchored to the
borehole casing by attempting to slacken the load bearing cable.
If it remains taut, the sonde is still loose within the borehole. Do
not proceed with installation in this case. Instead, you should
either move the instrument to a narrower section of the borehole
and try again, or contact Güralp Systems to fit a longer hole
lock, quoting accurate measurements of your borehole.
12.Power up the instrument from a suitable power supply.
13.Level and centre the sensor (see Section 3.5, page 46) so that it
can be tested.
14.Check that the sensor is functioning correctly by connecting a
meter or monitoring device to the sensor outputs. If the sensor
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