DCC/SOUND install Bachmann's new Class J (dialup warning)

[kristian]

J arrives today (according to USPS tracking), Eco-100, speaker, baffle already here. Pre-reading the Economai instructions/diagram reveals that it has 8 wires including a green/yellow ground wire, which is where they recommend connecting their included capacitor. However the Bachmann board in all the photos shows 7 solder pads and omits the ground. Am I correct in presuming that the ground is integrated in the Bachmann circuit board, or is there some other solder pad or contact point where the decoder's ground wire/capacitor should be attached?  I have done a number of diesel drop-in/sound decoder installations before, but this is my first hard-wire steam installation. Any advice (reassurance) is appreciated. Thanks in advance to anyone who can help clarify! 

[kristian]

Successfully installed a Soundtraxx Econami 100 DCC/Sound decoder with a 15mm round Soundtraxx speaker. This was my first hard-wire decoder installation. Many thanks to my fellow posters for the how-to pictures. The Soundtraxx hardware was a perfect fit, and I am happy to share some of the notes I made during the project. Hope this helps anyone else who is interested in adding sound to this nice locomotive!   

Disassembly Tip
Detach the tender loosely from the locomotive by removing the plastic sleeve from the tender's drawbar post, then slide the tender off of the drawbar. At this point the locomotive will still be attached to the tender by a wiring harness. Remove the tender body shell from the chassis (remove two screws from the bottom, then gently lift shell upward), and you will see a six-pin wiring harness at the front end of the tender. Gently slide the six-pin connector back toward the locomotive until it is free of the circuit board. Carefully slide the connector back out through the rectangular opening at the lower front end of the tender. You will now be able to handle the tender chassis and circuit board independently, which makes it much easer to install the decoder/speaker. The circuit board can be removed to access the speaker mounting area on the floor of the tender chassis. The speaker mounting area consists of a pre-molded cradle with a downward facing speaker grill. See below for details:

Speaker Install
The Soundtraxx 15mm speaker fits perfectly in the pre-molded cradle/grill that is built into the floor of the tender. To access the cradle, you must remove the retaining screw in the factory circuit board. Place the speaker face down in the cradle and route the speaker wires toward the front of the tender. Place a 15mm square piece of packing foam (1/8" thickness) over the top of the speaker magnet and then replace the circuit board and fasten the retainer screw. The packing foam will act as a lightweight cushion that serves two purposes: 1) it insulates the speaker magnet from the circuit board, and 2) it helps create gentle compression between the circuit board and the speaker magnet  that secures the speaker against the bottom of the cradle/grill. The tender body serves as an excellent speaker enclosure and the sound is awesome.

Capacitor Install
Once the speaker is in place and the circuit board is re-installed, cut the blue (common) and green/yellow (ground) wires from the decoder in half. Discard the cut green/yellow piece, then twist and solder one end of the cut blue wire with the shortened end of the blue wire coming out of the decoder, making this into one double-wire "tail."  Solder the other end of the cut blue wire to the positive lead of the capacitor. Solder the trimmed green/yellow (ground) wire from the decoder to the negative lead of the capacitor. Using double-sided tape, attach the capacitor to the underside of the coal load in the tender. Solder the double-wire "tail" of the blue wire to the far right #7 solder pad on the tender's circuit board.

Decoder Install
Once the capacitor is installed, use double-sided tape to attach the decoder diagonally and flat to the underside of the rear deck of the tender. Looking at the interior of the tender shell upside-down, the left front side of the decoder (8 output wires) should be tucked to the bottom left of the long screw-mounting lug in the center of the tender. The right back side of the decoder (four output wires) should be oriented toward the top right back corner of the upside-down tender deck. Follow the table on the Bachmann parts diagram and solder the wires according to the directions. Once all the decoder wires are soldered in place, re-attach the six-pin wiring harness from the locomotive, then flip the tender shell back over and onto the chassis.  The diagonal placement of the decoder on the underside of the rear deck of the tender will ensure that there is no interference with the tender's back-up light assembly.

Summary
After consulting the Soundtraxx tech support staff, who advised that their decoder should work just fine without removing the factory capacitors, I decided to leave the factory capacitors in place. Initially, the starting speed of the locomotive was a little high. However, I adjusted from 28 speed steps to 128 speed steps and then the starting speed was very realistic. I needed to adjust the chuff rate and some of the volume levels, but SoundTraxx has provided a great set of CV guidelines, and this is very easy to do using simple DCC programming. The locomotive runs and sounds great - very pleased with Bachmann and Soundtraxx!