July 8, 1963

SUBJECT:  JUNCTION BOX SPRAY SHIELD

FOR USE ON:  All V-75 Alternator Equipped Engines.

Due to various types of construction presently employed by outboard boat manufacturers, problems occasionally arise as to just where the Alternator Junction Box should be installed for proper ventilation (cooling).

Areas around the transom of some boats now being built have considerably more enclosure than was normally found in the past which can present problems when selecting a suitable junction box mounting spot.

The Alternator Junction Box has openings in the top and bottom of its base through which air passes to cool the heat sink, transistor and diodes. As these components become warm through normal operation - the heat they give off starts to rise and passes out through the vent opening in top, to the atmosphere. This causes cool air to be drawn in through the bottom, which in turn, creates a continuous cooling cycle (works like a chimney). Its understandable then why the junction box must be located so that it can "breathe".

To insure adequate cooling, most dealers have selected to install the Junction Box right out in the open on boats that have completely enclosed transom areas. There is nothing wrong with this type of installation except that its possible water spray may splash into the box through the top vent opening. Electrical components may start to corrode from direct contact by water. In salt water areas this is often a serious problem, since salt water has an almost devastating affect on electrical components which is sure to result in costly repair bills.

A simple spray protection plate can be made of 1/16" thick half hard aluminum to protect (shield) the top opening from water entry - yet still allow ventilation. See figures 1 and 2. Note that there is 5/8" clearance between the top of the junction box and the underside of the spray plate. This is adequate to allow normal ventilation.

The enclosed full size template can be used to make a spray plate identical to that shown in figure 1. Merely cut out template along solid lines and trace it on a sheet of 1/16" aluminum. Bend the aluminum as indicated by dotted lines, drill two holes as indicated and its ready to use.

Since the shield will be exposed we suggest having the piece fabricated by some local sheet metal shop. They have metal breaks for forming neat, accurate bends and can in all probability, do the entire job including cost of aluminum for $1.00 to $2.00, as long as they are furnished with the enclosed template.

Mount the spray shield between the junction box and boat. Hole dimensions indicated are spaced for alignment with two top junction box screws when mounting.

Over