Installation of Soundtraxx diesel module into the Stewart FT’s (ABBAset).  First take out both circuit boards of an A unit.  At the front  (nose end) of the zamac casting we need to take some material off the castings (go down .3 to .4).  This is where the casting starts to become narrow, just before the gear box.  Using a motor tool, after applying tape to protect the motor and gears, was the easiest for me.  I like to use masking tape with the sticky side up to catch filings.  Take off just enough so that the Soundtraxx module will fit.  Mount the module with the large connector facing up and the small connector (speaker wires) facing down.  I also made a small piece of styrene to fit over the two pegs on the black plastic that holds the motor, where the 2nd circuit board used to fit.  It’s about 2" long, fits inside the casting, and is used to lay the wires on.  I use a little clear RTV to glue everything together.  Clear RTV is best, because if mistakes are made you can just cut it off with a sharp knife.  The fit is tight and I had to reposition the module once to make it fit (reason for clear RTV).
     Solder the wires as per instructions.  For a front light I used a white LED.  Used the existing plastic rod (insert), cut off about a 1/16".from the back, bored a hole in the center, and put the LED in the hole, with a little yellow (clear) paint to take the extreme blue color off the white LED (this procedure is your choice for color of the light).  1K resistor works with the LED I had, LED is from "Jamco".  I RTV’ed the speaker capacitor to the frame also.  I then ran the speaker wires to a plug at the rear of the engine.
     Put the speakers in the B units.  Make as much room in the B units as possible, I took out all the plastic I could and glued the fuel tank on to the frame.  I had to do some milling as I used large speakers.  With the diesels use the biggest speakers you can get into the unit.  Sometimes 4 smaller ones will work as well as two bigger ones.  Test the sound before you put everything together.  The sound volume on the diesel module is not as loud as on the steam unit, so do some experimenting with speakers before you put everything together.  Getting the sound you want before final assembly is preferred and remember the shell will change the sound somewhat. I haven’t done this but leaving the port holes open on one side might make a difference, remember to put in the frame members if you do this.
     My setup is a ABBA so the following is the total set up.  Rear A unit has the Soundtraxx, two connectors on one side to get additional electrical  pickup from the coupled (drawbar) B unit.  Two wires on the other side for the speaker wires, use male for one and female for the other, that way you don’t get the wrong ones plugged in.
     Two wire connector on the other end on the second B unit, for the second speaker in that unit (wire speakers between B units in parallel).  Then two and two wires from that B unit to the last (or front) A unit.  There is a DH120 module just plugged into the NMRA socket on the front A unit.  Change the CV29 bit in the Soundtraxx unit so it runs backward, and presto - you have a dual powered, sound equipped ABBA FT setup.  Some speed adjustments probably are necessary, I haven’t got to this stage yet, also the Stewart circuit board is a straight connection from decoder to motor, no diode drop.  Uncouple between the two B units and you can run the units as AB and AB (after changing CV29, of course), however only one set will have sound (with one speaker).

NOTE:    Also worth adding is that I use a lot of a wire sold by NWSL (P/N 100079 Suprflx wire blk   2'  @0.95).  This is a #29 wire, silicone covered and multistranded, in other words, super flexible.  This works well for speaker to mini-plug connections, for replacing the wire from the trucks, and general decoder wiring in engines.  As long as the runs are very short the fact that it is 29 gauge does not seem to matter.  

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