Guralp Systems CMG-5T Compact - Manual (Page 6)

CMG-5T Compact
which is also provided on the calibration sheet.
2.2 Initial testing
To test the 5T Compact before installation, you will need a power source
which can deliver >100 mA at 10 to 36 V to cover initial transients and a
digital voltmeter (DVM) with 1 and 10 V ranges. Also ensure that the
supplied cable is connected with the correct polarity.
To make it easier to measure the output from the sensor, you can use a
Hand-held Control Unit or an improvised interface box, which can be
manufactured from a screw clamp connector block. This will simplify
the connections to the appropriate connector pin outputs.
1. Place the 5T Compact sensor on a flat, horizontal surface.
2. Connect the power supply, observing the correct polarity for the
cable supplied and switch on.
3. Connect the voltmeter to pins A and B of the output connector
(corresponding to the low gain vertical component). Measure the
output of the low gain vertical component. The steady output
voltage should be about zero (± 10 mV).
4. Repeat the measurement for the N/S and E/W low-gain component
outputs (pins C/D and E/F respectively).
5. Now turn the sensor on its side, propping it carefully to stop it
rolling.
6. The low gain vertical component should now read about –5 V,
corresponding to –1g.0
7. Roll the instrument until the N/S line is vertical, with N at the top.
8. The low gain N/S component should now read +5 V,
corresponding to +1g.
9. Roll the instrument until the N/S line is horizontal.
10.The low gain E/W component should now read +5 V.
If the performance so far has been as expected, the instrument may be
assumed to be in working order and you may proceed to install the unit
for trial recording tests. In many cases, there will be a slight offset to the
readings. This can be compensated for after installation, by adjusting
potentiometers (see Section 2.4 on page 9),
6 Issue E