M2/M3 BFV: FIRE CONTROL SYSTEM - OD1608 - LESSON 1/TASK 4
sight to day sight should not be boresighted until the 25mm gun is
boresighted.
Before starting any boresighting procedures, observe
this caution and warning:
CAUTION
20
Changes in the outside air temperature of
Fahrenheit (F) (11 centigrade) can cause
the
night sight to lose accuracy.
Boresight
the
night sight to day sight whenever the outside
air
temperature changes by 20F.
WARNING
Never look at the sun through the ISU; doing so
could cause blindness.
a. The Convenient Target Method.
After boresighting the 25mm
gun, the convenient target method of boresighting the night sight to
day sight is used if the visibility is good for 3280 feet (1000
meters). To boresight, using this method, follow these steps:
(1) Check that the NIGHT VISION PWR switch is in the ON
position.
It should have been turned ON during the boresighting
procedures for the 25mm gun in order to give the ISU time to cool
down for operation.
(2) Move the SENSOR SELECT switch to NIGHT (figure 24 on the
following page).
(3) Turn the BRT (brightness) knob (figure 25 on the following
page) to adjust the brightness.
(4) Turn the CON (contrast) knob (figure 25)
to adjust the
contrast.
NOTE
If the focus knob is turned to the left more than
seven to nine turns from a fully right position,
a freewheeling effect will be noticed.
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