Si-tex SP38, Installation And Operation Manual, Page: 50 / 193

Sitex SP38 Installation and Operation
Document PN 29010101 V1r0
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Signal Processor Unit
Mounting
The SPU should be mounted in a clean and dry area, away from heat, moisture, and liquids of
any kind. The SPU should be centrally located, and mounted far enough away from your
vessel’s compasses so as to minimize any possible electrical interference; a good rule-of-thumb
is at least 1 metre (about 3’), but see the
Compass Safe Distance
s
section for specific values, if you do not have that much space.
The SPU can be mounted vertically on a bulkhead or horizontally on a deck or shelf.
•
If mounted vertically, it should be positioned so that all wires and cables will exit from
the bottom of the SPU (after running sideways, left and/or right as appropriate, from the
SPU connectors under the SPU’s wiring cover).
•
If mounted horizontally, all wires and cables should have a drip-loop formed in them.
Each SPU is shipped from the factory with a package of four (4) mounting feet and a separate
instruction sheet that includes dimensions for drilling holes to fasten the feet to the vessel.
Wiring the SPU – General Information
Due to the relatively high current requirements of an autopilot compared to many other types of
electronic equipment, Using the correct size of wire to connect the various components is very
important. Undersized wiring will result in power losses which can affect overall efficiency and
performance. Refer to the table below. If in doubt, contact your Sitex Dealer for help.
Once the SPU is securely mounted, you can begin wiring the various components of the
system, one at a time.
Function / Use Type / Gauge
SPU Power Supply 2 X 12 AWG
Steering Drive: 12/24 VDC Solenoid Valve 3 X 18 AWG
Steering Drive: Reversing Motor
2 X 14 AWG
(refer to the instructions supplied
with the Drive Motor)
Rudder Follower 3 X 18 AWG Shielded cable
GPS, Chart-plotter, Navigation Computer 2 X 24 AWG Shielded cable
Rudder Angle Indicator 2 X 24 AWG
Table 1 – Minimum Recommended Wire Gauges
Connectors on the SPU
Each connector is a pin receptacle, with the pins sized according to how much current will be
carried (bigger pins for higher current). Each pin has a signal name, rather than a number, to
make it easier to match wires with pins (see connector label, below).
Each pin receptacle mates with a matching plug, which in turn has screw-clamp terminals, into
which the wires from the external equipment and devices (battery, drive system, compasses,
etc.) are inserted. The plugs allow quick installation and removal of system wiring, yet are fully
secure, once the various cables are strain-relieved and the wiring cover is re-installed.
The SPU is shipped with all the plugs required, pre-installed on the matching receptacles.