NorthStar Navigation installation manual Wiring, Connecting the 491 to the 961/962

SECTION THREE — Installing the 491

Wiring the 491

CAUTION!

Make sure that fuse or circuit-breaker protection is provided at the power source.

Electrical power requirements

Connecting the 491 to ship’s power

The majority of installation problems are caused by shortcuts taken with system cables. When installing the 491, be sure that you:

•assemble connectors carefully

•don’t make sharp bends in the cables

•leave service and drip loops, so that moisture won’t run down the cables and into the 491 or the navigator

•tie-wrap all cables to keep them secure

•if cables are shortened, lengthened (not recommended), or re-termi- nated, seal all wiring splices

•prevent interference from the transducer cable

The 491 is a negative-ground system that is reverse-polarity and over- voltage protected. The unit requires 8 to 36 VDC power at 8 Watts.

The connection between ship’s power and the 491 requires the 10-foot (3-meter) power cable supplied with the 491.

The wires in the power cable must be connected as follows (black and white can be connected together at the power source):

•Red → Positive (+) (fused lead)

•Black → Negative (–)

•Green → Ground (earth)

NOTE:	The 491 should be grounded to	the vessel to eliminate interfer-
	ence. Secure the green wire to	the vessel’s nearest grounding
	point. Without an earth grounding, performance may be degraded.

Connecting the 491 to the 961/962

The connection between the 961/962 and the 491 uses the 10-foot (3-meter) data cable supplied with the 491. The cable connects to the P1 slot on the back of the navigator.

The cable is shipped with a round 6-pin connector that attaches to other Northstar navigators. To install the 491 with a 961 or 962, you must cut off and discard the 6-pin connector, and wire the cable as shown below.

Be sure you don’t cut off the 8-pin connector that plugs into the 491!

Figure 8 below illustrates the wiring at the 961/962 end of the cable. Table 4 describes the pin’s functions.

491 INSTALLATION MANUAL Revision A PAGE 15