GW Instek GDM-350B - Manual (Page 7)

OVERVIEW
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7. When each measurement has been completed, disconnect the test leads from
the DUT and then turn the power off from the meter. Remove the test leads
from the input terminals of the meter. This is vital for high current
measurement.
8. When the meter is working at an effective voltage over 60V in DC or 30Vrms in
AC, special care should be taken.
9. Do not use or store the meter in an environment with high temperature and
humidity. The performance of the meter may deteriorate if dampened.
10. The internal circuit of the meter should not be tampered with. To avoid
damage to the meter when cleaning, use soft cloth and mild detergent to clean
the surface of the meter when servicing. No abrasives or solvent should be
used to prevent the surface of the meter from corrosion and damage.