TM 5-6675-250-20
1 - 1 1 . T E C H N I C A L P R I N C I P L E S O F O P E R A T I O N ( C o n t i n u e d)
(6)
(7)
(8)
(9)
Brake on indicator (6).
I l l u m i n a t e s w h e n t h e M O D E S E L E C T s w i t c h i s p l a c e d t o B R A KE
O N , i n d i c a t i n g t h e b r a k i n g s e q u e n c e . A t t h e c o m p l e t i o n o f t h e s e q u e n c e , a 9 0 - s e c o nd
dynamic braking of the gyro motor, the BRAKE ON indicator light will be extinguished.
Theodolite brightness control (7).
R o t a t i n g t h e c o n t r o l c l o c k w i s e i n c r e a s e s t h e i n t e n s i ty
of the light.
Reset switch (8).
Enables the operator to reinitiate the gyrocompass interval. Pressing the
R E S E T s w i t c h e x t i n g u i s h e s t h e R E A D A Z I M U T H i n d i c a t o r a n d r e i n i t i a t e s g y r o c o m p a ss
action for a minimum of 45 seconds.
Bias control (9).
Following self-test operations, the instrument is adjusted for bias through
the BIAS control. Rotating the BIAS control clockwise will move the pointer to the right, and
counterclockwise rotation will move the pointer to the left. Careful attention should be giv-
en to positioning the pointer in the center of the scale to ensure the highest degree of accu-
r a c y.
(10) Bias lock (10).
Mechanically holds the BIAS CONTROL in the set position to prevent an
a c c i d e n t a l
m o v e m e n t.
( 1 1 ) R e a d a z i m u t h i n d i c a t o r ( 1 1 ).
I l l u m i n a t e s w h e n t r u e n o r t h h a s b e e n o b t a i n e d ; l i g h t is
applied automatically to the theodolite scale for azimuth reading.
(12) Gyro sync indicator (12).
Illumination indicates that the gyro motor has attained synchron-
ous speed. When the GYRO SYNC indicator illuminates the CAGE-UNCAGE knob the GRU
is to be rotated to UNCAGE (clockwise rotation).
(13) Latitude select switch (13).
Provided to maintain instrument operating time at different lat-
itudes of operation. The switch is adjustable with a screwdriver and contains eight posi-
tions. The switch positions and corresponding latitudes of operation areas follows:
Switch Position
Latitude of Operation
0
25
4
0
50
6
0
6
5
70
7
5
0-15 degrees
15-30 degrees
30-45 degrees
45-55 degrees
55-63 degrees
63-67 degrees
67-73 degrees
73-75 degrees
1-17
