Sound Decoder Installations

Auscision N - Tsunami Decoder

With this installation I used a Tsunami EMD645 sound decoder with the Leslie RS5T horn as a selectable option. In particular, I used Tsunami model TSU-AT1000 with the product code 828041. This decoder is in fact formatted specifically for Atlas brand models and is installed by completely removing the existing circuit board and installing the Tsunami board as a complete replacement. The advantage with this approach is that you save a lot of much needed space because in the Auscision N case, the Tsunami decoder is actually smaller than the board it replaces. Also, the Auscision N simply does not have enough space for a Tsunami TSU-1000 plug in decoder. You could use the TSU-750, but this decoder has a lower current rating than the TSU-1000 and TSU-AT1000 decoders.

The first step then is to remove the body from the loco according to the Auscision instruction sheet. However, be aware that the body of new locos seems to be stuck on with glue in places, so a lot of force with a small screwdriver beneath footwalks is required. Note also that there are six screws and the coupling boxes to remove first. The footwalks come off with the body (unlike some Austrains models like the NR and c).

The above picture shows the Auscision N with the body off. Note that the wires running between the LEDs mounted in the body and the main board mean that the body is not completely detached from the chassis. However, more working space can be created by prising the main board off its mountings with a small screwdriver.

Next is the job of removing the main board completely. Before doing so, label all the wires and for good measure, take careful written notes of where all the wires go. My notes indicate that white and yellow wires generally went to the anode (or positive) ends of LEDs. Black wires went to the cathode (or negative) LED ends. Red and green wires go to the headlight switch underneath the loco. Red and black wires are used for track pick up with a red wire being used on the right at the front and the left at the rear. Black and blue wires are used for the motor.

The above picture shows the Auscision N with the main board removed. The first thing to note is that there are more connection points on the Auscision board that there are on the Tsunami board. So there is a bit of point to point wiring required. Firstly, to the headlight switch. This switch works on the postive feed to the headlights at both ends. So the anode (or positive) wires for two headlights need to be connected together and to one of the switch wires. Another thing to note is that Tsunami board does not provide a rear light connection point at each end. Rear lights of course simply come on with the front lights, so the cathode (or negative) wires for the front lights at one end need to be connected to the cathode (or negative) wires for the rear lights at the other end. This needs to be done for both directions of travel.

Careful tracing of the main board circuitry reveals that there are no LED dropping resistors on the Auscision board so none will be necessary with the Tsunami installation

I decided to use the chassis rails as the walls of my speaker enclosure with an aperture made of styrene. This enclosure would not be actually airtight but should create sufficient separation of air between the front and rear of the speaker.

The above picture is of the speaker I used which was kindly given to me by the people at Branchline in Croydon Victoria. It measures 14mm X 25mm and just fits in between the Auscision N chassis rails where they thin out towards the bogies.

The above picture shows the speaker aperture. Note the holes for the track and speaker wires. Note also the nicks for the frontlight switch wires and the body mounting screw.

The Soundtraxx small oval speaker product code 810112 does a similar job if the corners of the speaker frame are trimmed a little at one end. The Soundtraxx 810121 self adhesive gasket kit is recommended for use with the Soundtraxx speaker. Not only does a gasket provide a bit of space for the speaker cone it also does an excellent job of sticking the speaker securely to the styrene.

Now its a case of wiring in the new board. Because the new board is smaller than the old board the wires from the LEDs in the body need to be extended. Extending these wires should not be overdone. I actually positioned the old board over the new one and cut wires to suit the size different plus a bit for solder joints.

The above picture shows the extension wires in place plus the wires running between the headlights and front and rear lights described earlier. I have used heat shrink tubing over the solder joints. Note that the circuit board mounting tabs are not the right distance apart for the new board so one of the tabs must be broken off.

The above picture shows the new board taped in place. Insulation tape is also used to position the Tsunami's boards flying capacitor and to tidy up the wiring a bit.

Test the loco before finally replacing the body.

The final result: