SoundTraxx Tsunami decoders

Frequently Asked Questions

Getting the most out of your Tsunami

Bruce did a clinic for the NMRA AZ Division in November, 2010. To view a PowerPoint version of this clinc, CLICK HERE.

Cooling my Tsunami

The high clock rate necessary for the Tsunami decoder to deliver its marvelous sound generates a lot of heat. The longevity of your decoder and the reliability of its operation is enhanced by keeping the decoder cool. There is a heat sink plate built into the shrink wrapped Tsunami decoders (TSU-750 and TSU-1000). When we install one, we do everything possible to mount that side of the decoder to something to carry away the heat, like a weight or metal shell, even to the point of mounting the Tsunami on a piece of brass connected to the loco shell. If you do the same, your Tsunami will be happier!

I didn't order the CD with the Tsunami Manuals!

You can download the Tsuanmi manuals from the SoundTraxx Web Site -CLICK HERE.

How do I wire my Micro Tsunami?

This question comes up frequently, as the Micro comes without the capacitor installed. You can download the Micro Tsunami Quick Start guide from the SoundTraxx Web Site - CLICK HERE.

I've captured the wiring diagram from that document. Click on the drawing to view a larger version.


I've lost the card that came with my decoder!

This information is absent on the SoundTraxx web site. We cannot provide as high quality a print as if we had the original artwork. But we do what we can to help. Bruce has scanned some and they are just a click away:


Setting Addresses on Digitrax Super Chief Sets:

The DCS from Digitrax does not conform completely to the NMRA Recommended Practices for programming tracks.  But The Tsunami does. Early Tsunamis cannot have CV 17 or 18 (long, or 4-digit, address) programmed on the programming track with the Digitrax system. Rather than leaving their customers in a bind, SoundTraxx "jimmied" later units to overcome Digitrax' weakness. 

WORKAROUND: Program the 2 digit address of your choice on the programming track. Move to the main. Confirm operation of your loco on the main. Select Programming OPS Mode for the 2 digit address you've set into the loco. (Po display) Select AD2=???. Press the right knob to get into the 4 digit mode. Enter your desired 4 digit address. When your DT400 asks if you want to activate the 4 digit address, answer "Y". 

If you are using DecoderPro, as I do, here's what I find works. Set the 2 digit address on the programming track with the software and save the file. Move to the main and select programming on the main. Set the 4 digit address and select 4 digit addressing on the main. Quit and save the computer file. Operate the loco on the main with the 4 digit address. Reopen the computer file and continue customizing the loco on the main.

I Can't Read My Tsunami's CVs

Your command station (DCC set) probably was not designed to operate with these new sound decoders. Many aren't. You may need a Programming Track Booster to read your decoder. CLICK HERE to learn more.

My Sound Isn't Loud Enough

On-board loco sound in HO and smaller scales will NOT be loud enough to be over the crowd at a meet in a large room. The idea is to provide enough sound to be heard in the neighborhood of the loco. One club in the Phoenix AZ area has a rule: "If it can be heard 5 feet away from the loco, it is TOO LOUD!" This is a good definition of "scale sound" - that is, sound which is correct for the scale you are modeling.

With this introduction, Bruce wants to explain that he finds the Tsunami MORE THAN adequate to fulfill these needs. In installations which fall short, he normally finds that improper speaker installation is the culprit.

Bruce did a clinic at the NMRA National Convention in Cincinnati on the installation of speakers in HO scale locos. He updated it for the Detroit convention. There is a page on this web site that details some of the methods presented in that clinic. CLICK HERE to see it.

I Can't Get My Loco to Run Well Slowly

The Tsunami has a great BEMF control system, but, like all finely tuned items, it needs to be compatible with your loco. Here's how you get them happy with each other. Make sure you have BEMF enabled (the factory default).

  • Turn Off any speed tables with CV29
  • Set CV2 to 0
  • Shut off momentum 
    (CV3 = 0; CV4 = 0)
  • Go to Programming on the Main (OPs mode for Digitrax), preferably using DecoderPro
  • Set CV209 to 0
  • Set CV210 to 0
  • Set the loco moving forward on speed step 1
    (128 step mode recommended)
  • Adjust Kp (CV209) until the loco just moves, very slowly - may be jerky
  • Adjust Ki (CV210) until the loco smoothes out

If you want EXTREME low speed control, you can adjust from the above settings. Bruce suggests that you reduce CV210 by 1 and then adjust CV209 up until you get movement.

To view a Windows video of what can be accomplished this way, CLICK HERE or, you can view the HD version on You Tube, just CLICK HERE!

Yes, this loco is moving on speed step 1 in 128 step mode. 
Once you have done the above, you can adjust the steam chuff rate to match the wheel rotation (assuming you aren't using a cam) by:
  • Set a medium slow speed on the loco - about step 10
  • Adjust CV116 for the proper chuff rate
    (4 chuffs per revolution for most rod locos)
The sound will be in sync for this speed step only - if the loco runs slower, it may fall off - much faster and you won't be able to count the chuffs relative to wheel rotation. Bruce finds this provides the best balance!
  • Reset momentum 
    (Bruce recommends CV3 = 40; CV4 = 12 to 20 for diesels)
  • Restore speed tables (make sure speed step 1 = 0) or otherwise limit top speed to your liking - see the next section.
A trick way to limit top speed

For many of the locos I’ve set up I find that a two point (or three point) speed curve will do just fine. The Tsunami don’t support CVs 5 and 6 for the three point curve. In the last section, I showed you how to set up the bottom speed so your loco will crawl. Here’s how I limit top speed, once that is done. After I adjust CV29, I use Programming-on-the-Main (Ops mode to Digitrax users).

Read CV29 and add 16 to the number that you read - store the new number back in CV29. (Use Speed Curve in DecoderPro)

Set CV25 = 2 (Linear Speed Curve in DecoderPro)

Set CV67 to CV94 to zero (I hear you asking, “Why?” Well, setting CV25 = 2 disabled the speed table, so I set the table to zero, making for a quicker read of these CVs in the event of a READ ALL request. You can choose to do so or not.) To do this in DecoderPro, set all speed sliders to zero.

Then I use CV66 (FORWARD TRIM) and CV95 (REVERSE TRIM) to adjust the speed in each direction. A value of 128 in each of these CVs will give you the fastest speed possible, given all the other adjustments that have been made. A value larger than 128 will not increase speed. However, in most cases, I find locos run too fast. I adjust the values so that the loco runs as fast as I want when the throttle is wide open.

For yard locos, I like a top speed of about 30 SMPH - about 2 seconds for the loco to pass a fixed point. This usually requires a value about 40 to 60 in CV66 and CV95.

For early diesel era locos, I like a top speed for road power about 60 SMPH - about one second for a loco to pass a fixed point. This usually requires a value about 50 to 90 in CV66 and CV95.

Newer diesels may want a bit faster top speed, but only a touch.

Can I shorten the wires to the external capacitor?
The answer is yes!
However, Bruce suggests you do as he does. Whenever he is shortening the wires or adding additional capacitance, he works on the capacitor end of the wires, leaving them attached to the decoder. Getting a soldering iron near one of these fine trace boards can result in all sorts of unwanted issues. Be safe; stay on the capacitor end of the wires.
How do I set my Tsunami up to sound like dual prime movers?

There are many situations where you might want to emulate dual prime movers - locos with two internal prime movers (EMD E-units, Alco's DL series, EMD's DDA40X, etc.) or A-B sets where you only put sound in one unit. The Tsuanmi reverb comes to the rescue! I recommend the use of DecoderPro to set Tsunami CVs in all situations. So, here is the DecoderPro page - those in orange or blue are the changes:

DecoderPro Reverb - multiple prime mover-0

The values are:
CV 161 = 7
CV 162 = 255
CV 163 = 255
CV 164 = 0
CV 171 = 255

My loco stalls on turnouts or doesn't run smoothly!
I want to add more capacitance

This topic has moved to a more general setting: CLICK HERE to go there

Do Tsunami decoders support LEDs?

In a word, YES! None of the DSD-LC issues with LEDs exist with the Tsunami decoders, steam or diesel. Their lighting effects (Mars, ditch, etc.) can be optimized for incandescent or LED lights. So, just install your decoder with the resistor and LED that you would otherwise do and set it up the way you want.

How do I connect LEDs to my TSU-AT1000?

This is covered in step 10 of the installation card, but it isn't perhaps as clear as it could be.

Connect the Anode (blue or positive or long) lead of the LED to the rounded (function common) terminal on the decoder as shown in the photograph below. Use a dropping resistor (750 to 1500 ohms) in either lead of the LED. Bruce prefers to put it in the blue lead, minimizing the damage caused by a short in the circuit anywhere. If you connect it backwards, no harm, it just won't light.


For the TSU-GN1000 version, use the squared pad, as shown on the right above, and the +14V pad located elsewhere on the board.

I want an 8-pin NMRA (NEM652) plug on my TSU-1000!

That's easy. The TSU-1000 Tsunami has a 9-pin JST connector on it! All you need to do is to expose the connector without removing excess shrink tubing and plug in the JST Harness of your choice! Here's how (CLICK on photos for more detail - use your BACK button to return):

First you use your HOBBY KNIFE to score the shrink across the 9-pin connector.


Next snip and peel the shrink back from the top and two sides of the connector. CAREFULLY trim the bottom, making sure NOT to dislodge the heat sink (the flat piece of metal on the bottom of the decoder as pictured here). If you dislodge the heat sink, the decoder will almost surely fail and not be covered by warranty.


My Micro Tsunami loco starts and stops randomly
My Micro Tsunami overheats

The TSU-750 Tsunami is very sensitive to heat. There is a small heat sink inside the shrink wrap - the side that is totally flat. If you are having problems with your loco running for a bit then stopping and starting again and running, probably you are tripping the thermal protection inside the TSU-750. You need to get the heat out of it! Stick the heat sink side of the decoder to something large and metal if at all possible. I recommend thermally conductive epoxy or carpet tape or bathtub caulk for this.

I finally found the ultimate solution to this issue!


Seriously, my 3 GHz Pentium 4 dual processor fan died and I had to replace it, so I stuck a micro Tsunami to the used heatsink with thin carpet tape just for fun! REMEMBER model railroading is FUN!

My diesel Tsunami runs away after a power loss.

The diesel Tsunami was designed to resume at the speed selected after a power loss, rather than beginning with a startup sequence while running down the track. If you have selected a non-zero value for acceleration momentum (CV 3) and the power loss occurs before the loco comes up to the selected speed, after the power loss it will run at the selected speed immediately! Some folks have reported loss of acceleration and deceleration momentum settings, but we have yet to confirm this. Every test we've run or seen run revolves around not being up to the desired speed when the power loss occurs. If you add a capacitor, you can reduce the occurrence of this issue.

Using a Tsunami as a sound-only decoder

Many folks decide to use these fine sound decoders for their sound generating capabilities and, perhaps, lighting effects. Here are some suggestions:

  • Motor - If you put a 100 ohm 1/2 watt resistor between the gray and orange motor wires or contacts, you can then get acknowledgments back when you program.
  • If you set the Tsunami for Speed Table operation with the USER SPEED TABLE selected and set all speed steps to zero, then you won't be using your DCC power to heat up the resistor when you are running! To do this, read CV 29 and add 16 to that value and write the result back into CV 29. Then set CV25 = 16 and set all the CVs from CV 68 through CV 94 to zero.
Using a Tsunami with an external amplifier?

The Tsunami can be used with an external amplifier. Build a simple circuit with a transformer to isolate the ground and adjust the impedance. Connect it to a line level input on your external amplifier. See a videoCLICK HERE. The same circuit that was developed for the DSX decoder will work for the Tsunami, just eliminate the capacitor as it is unnecessary. Here is  the schematic.

Copyright © Bruce F. Petrarca 2007 - 2019; All Rights Reserved