Skinny Quantum –U/W for Athearn SD40T-2
Posted on 17. June 2010
See also Quantum Revolution.
Revised June 17, 2010
Steve Gill – Ulrich Models
Abstract
This procedure documents the installation of the Ulrich Models SD40T-2 QSI Sound Kit into an Athearn RTR SD40T-2.
The Athearn SD40T-2 is a nice looking locomotive. However, Athearn left very little room inside for installing a sound decoder and speaker. The body is narrower than most diesel models therefore many of the usual speakers will not fit. The speaker used in this kit is the TDS Mini Oval and enclosure. Although a small speaker, it has very good sound. In fact, it has amazing sound for its size.
The kit includes the QSI U/W decoder. The U/W decoder is the Revolution U decoder without the JST connectors making the decoder quite thin. There is almost no room between the Athearn Lamp board and the roof so it takes a thin decoder to fit and clear the roof. The sound file selected is the SD40-2 QSI file. This is one of the newer QSI sound files and it produces great sound in this model.
The Athearn RTR board only has outputs for a headlight and backup light. The model wiring is such that the lights above the cab come on with the headlight. Additional wiring and some resistors are required to make the lights above the cab independent and function as mars or strobes.
Figure 1 – Install Kit
The unused wires on the rear of the decoder are shortened and taped with Kapton tape to make the installation tidy. We ship the decoder in this configuration.
Note: Be careful when doing the install. The cab window sunshades have a fragile mount and can be damaged easily.
Installation
The first step is to separate the shell from the frame. This is done by removing the couplers and sliding the shell off.
The rear weight has to be removed to make room for the speaker and to prevent the sound from being blocked. The rear track power leads must be disconnected to remove the weight.
To remove the two track power leads, slide the two retainer clips off. This is sometimes easier said than done. Next remove the screws that hold the weight. Once the weight is removed, the track power leads can be reattached using the clips or by soldering them on.
This installation uses the 8-pin socket on the Athearn board. The 9-pin JST harness is not used and is in the way. It could be folded over towards the cab to get it out of the way but I recommend removing it. To remove it, take a pair of flush cutting diagonals and clip the wires at the board. Check to make sure there are no strands left dangling, which in some cases can cause a short.
Figure 2 – Installation
The speaker is on a connector so it can be installed as shown and then connected later. A small piece of double-sided tape is included for mounting the speaker. Something like Goop or E6000 will also work.
Figure 3 – Speaker Install
Next plug the decoder in and place it on the circuit board as shown. Secure with a piece of tape. I used electrical tape. Subsequently secure the capacitor by taping it to the frame at the rear of the decoder.
Connect the speaker and you are ready to put the shell back on.
Completed Installation
