TM 5-6675-330-12&P
7. Power Fuse.
9. Determination of Total Offset Correction.
The power circuits of the instrument are protected
against overload by a power fuse. If the power
fuse should fail, power is no longer applied to the
internal circuits, If no response is seen when the
PWR switch (3) is actuated, check or replace fuse,
If more than one fuse failure occurs, the instrument
should be returned to depot repair facility for
repair.
8. BATT Light.
A low battery condition is indicated by flashing of
BATT light (4). Reliable range measurements can
still be made with the light flashing; however, the
instrument will go into an automatic power-off
mode when battery voltage falls below a preset
limit. At this point, the BATT light will glow brightly
and steadily, Connection of a fully charged bat-
tery pack or auxiliary source to the instrument will
permit resumption of normal operation.
NOTE:
Under low ambient light conditions a faint glow
may be observed, This is normal and does not in-
dicate a low battery voltage condition,
Although the total offset correction has been
entered into the instrument before shipment from
the factory, the accuracy of the total offset should
be verified under actual operating conditions.
(Refer to performance Check,) If no known base
line is available, use the following procedure.
The true distance between the vertical axis of an
EDM instrument and the vertical axis of a retro-
reflector will usually differ from the instrument’s
displayed range unless the proper offset correction
figure is used. The difference is due primarily to
two factors: retro-reflector prism offset, and
instrument offset.
A prism offset is positive (the effect of the prism is to
increase the indicated range beyond the true
value),
If a known base line is not available for
determination of the ranging accuracy of the
instrument, the following peg test may be used to
determine the total offset correction required:
NOTE:
For optimum results make A=60m * 1m,
B=40m* 1m, and C= 100m* 1m, or multiples
thereof.
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