Installation of a DSD150 and speakers in Stewart F3 -F9 A units.

Preface
The following installation instructions have been provided to Tony's through the generosity of Ogden Lamont.

Fig. 1

The installation requires modification to the chassis, rear motor mount, rear flywheel, and cab window insert casting.

CHASSIS MODIFICATIONS

Fig. 2

The chassis requires modification to make room for the speaker assembly in the cab area. The modifications are best done on a milling machine or a milling attachment of a lathe. However, they can be done manually with a hacksaw and file if care is taken.

The side walls need to be cut back about 0.50", and a .035" recess made in the top surface. These modifications are shown in Fig. 1. The recess should not exceed .035' deep, otherwise the speakers may touch the front flywheel. The dimensions shown assume a speaker assembly of two Soundtraxx 1" diameter speakers glued back to back to a 1" diameter by .250 " long plastic spacer. A .125" wide by .062" deep grove should also be cut in both sides of the transverse bulkhead just forward of the front flywheel. This allows for wiring clearance under the speakers.

Depending on the actual width of the DSD150 decoder, the inside of the walls of the chassis at the rear, may need a little filing to allow the decoder to fit between the walls.

REAR MOTOR MOUNT MODIFICATIONS

The upward protrusion that was used to mount the Stewart circuit board need to be trimmed of to provide clearance for the decoder. This is easily done with a pair of rail nippers.

REAR FLYWHEEL MODIFICATIONS

The larger diameter of rear flywheel needs to be turned down to match the smaller diameter, inorder to make room for the decoder. The rear of the flywheel then needs to be given a radius of about .250" to clear the shrink tubing on the decoder. This radius is required if the decoder is installed "upside down" with the protrusions pointing down. This installation provides clearance for the fan housing on the shell, and makes for more direct wiring for the power pick up leads. The decoder may be mounted "upright", and the radius is then not required. However, this will probably mean trimming the underside of the shell fan housing to clear the decoder.

CAB WIDOW INSERT CASTING MODIFICATIONS

Fig. 3

This insert needs to be trimmed to provide clearance for the top of the speakers. The initial cut can be made with rail nippers, and the additional material trimmed with a Dremel tool.

ADDITION SPEAKERS IN B UNITS

Fig. 4

Additional speakers can be added in dummy B units. The enclosures shown were made of .030" styrene, with an overall width of 1.100" to fit inside Stewart, Athearn, and Highliner shells. This required trimming the Soundtraxx 1.7" x 1.1" elliptical speakers to about 1" in width.

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