Raymarine autopilot ST4000+, Service Manual

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Autopilots
18 Autopilots Service Manual 83115-1
3.3 Setting Belt Tension
The purpose of the belt tensioning procedure is to ensure that:
1. The belt is sufficiently tight to transmit the normal maximum drive
torques.
2. The belt is not over-tightened, as this will increase the backdrive load to a
level where it can be felt on the vessel’s wheel.
Tools required:
4000 Drive unit torque fixture
Service tool number - T033
4000 Drive unit torque adjuster
Service tool number - T032
Motor drive box and ammeter
Motor drive box
FS1
12V
BATTERY
Red (ZO78)
Brown (Z077)
Blue
ACTUATOR
15A
IC1
LM396K
D1
SW1
R1
121R
+
MR752
C1
+
4700uF
C2
4.7uF
R2
+
845R
C3
+
22uF
C4
4.7uF
R3
1KO
D2384-1
Figure 9. Motor drive box circuit diagram