(5) If the mirror is damaged, replace it.
(4) Remove the setscrew (10) that secures the
Cement it in place in the mirror housing with
axis pin (11) in the mirror housing (13).
s h e l l a c . Allow it to dry thoroughly after carefully
(5) Remove the pin (11) from the mirror
w i p i n g off any excess shellac.
housing (13).
(6) Remove the mirror housing (13) and
d. Reassemby.
mirror (14).
( 1 ) Position the mirror housing (13, fig. 4-3)
in the sleeve (15) and install the axis pin (11) in the
NOTE
assembly.
The mirror is cemented in the mirror housing and
(2) Install the setscrew (10) to secure the pin
cannot
be
removed
unless
the
cement
is
carefully
softened
with
alcohol.
(11).
(3) Install the machine screw (12) in the
c. Cleaning, Inspection, and Repair.
m i r r o r housing (13) and adjust the tension on the
(1) Clean all metal parts with an approved
axis pin (11).
c l e a n i n g solvent.
( 4 ) Install the retaining clip (9) in the sleeve
( 2 ) Clean the mirror by breathing on it and
p o l i s h i n g with a chamois skin, lens tissue, or soft
(15).
( 5 ) Install the threaded retaining bushing (8)
cloth.
o n the threaded sleeve (15) by turning in a clock-
( 3 ) Inspect the mirror for cracks, breaks, and
w i s e direction.
loose backing. Inspect the mirror housing and
e. Installation. I n s t a l l t h e i l l u m i n a t i o n m i r r o r
s l e e v e for bends, cracks, and scored bearing sur-
assembly on the theodolite as outlined in paragraph
faces.
(4) Inspect the pin for wear and scored
3-24.
surface. Remove burred edges with a swiss pattern.
f i l e and smooth out minor dents.
Section
IV.
ILLUMINATION
SYSTEM
4-9. General
h o l d i n g washer (37) and separate the rheostat (9)
f r o m the battery box (33). Unsolder the cable (8)
The illumination system is used to make night
f r o m the rheostat (9). Remove the two screws (31)
r e a d i n g of the plate and collimation levels and to
a n d lift out the trunk (30).
i l l u m i n a t e the horizontal and vertical circles. The
(3) Remove the screw (11) and lift the contact
h a n d lamp is used to illuminate the circular level
(10) from the battery contact (22). Remove the two
and to provide general illumination
for
the
s c r e w s (13) and lift the two sockets (14) from the
n i g h t t i m e operation of the theodolite.
b a t t e r y box. Remove the four setscrews (15) and
CAUTION
s e p a r a t e the cables (8 and 12) from the sockets.
Do not use the hand lamp in close
Bend down the wire clips and lift the cables (8 and
p r o x i m i t y to the compass.
12) from the battery box (33).
4-10. Battery Box Assembly
( 4 ) Remove the two screws (31) and lift the
a. Disassembly.
t r u n k (23) part way from the battery box. Remove
(1) Remove the screw (11, fig. 4-4) and
t h e screw (26) releasing the spring (25) from the
d i s c o n n e c t the two contacts (10). Remove the two
t r u n k . Remove the three screws (21) and separate
nuts (5) and washers (4) and lift the contact springs
t h e battery contact (22) from the trunk.
( 3 ) , contact (2), and insulation (1) from the studs
inside the battery box (33).
(2) Remove the taper pin (36) and setscrew
(34) from the rheostat knob (35). R e m o v e t h e
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