Scarpia's MINIVerse - Model Railroading


Bachmann Spectrum 2-8-0 to Tsunami equipped Sound DCC

I've picked up a couple of these for cheap (under $60) on eBay, brand new in the box. The basic Bachmann decoder is functional. I thought, however, that this might be a good first project (dipping into sound equipped locos), and replace the decoder with a sound capable one.

I spoke to Norm at Tony's Train Exchange, who recommended a Tsunami light steam decoder, 1 inch speaker, and a Digitrax DHWHPS harness

The exploded tender, and components

  1. Tender frame with factory circuit board (decoder removed)
  2. Digitrax DHWHPS
  3. Tsunami light steam decoder
  4. 1 inch speaker

Start off by removing the body of the tender from the floor. There is single screw on this model just behind the front truck; once this is out, you will see to hinging tabs on the back. I just nudged those forward a bit with a screwdriver, and the top pop right off.

The first step is unplugging the stock decoder (upper right, shown below) from the circuit board in the tender. This just simply pulls out from the 8 pin connection on the board (the Tsunami is in the purple shrink wrap)

Next, cut back the purple shrink wrap on the Tsunami to expose the plug for the wiring harness.

and carefully remove the wiring whip that comes stock with the decoder.

Next up, plug in the Digitrax DHWHPS wiring harness to the Tsunami, and on the other end, plug in the 8 Pin into the circuit board on the tender.

Remove the coal load from the Tender (it pops out, there is a tab towards the rear.

I ran the two purple wires through the large opening in the front, and soldered each of them to the connection spots on the speaker.

And the test run - I left the tender "loose" to test it; I reprogrammed the decoder (programming track in the front of this picture) and than had it on the main line. It worked first time out!

After a few runs, I took it off the track, and reassembled the tender properly. The decoder and speaker were positioned with foam 2 sided tape, and all put together. The sound is better with the tender put together, and I spent the next hour or so playing with CV values on the sound side (volume, etc.)

Note that you need a programming track booster to program these decoders, I have a Soundtraxx Tsunami 829002 PTB-100, that worked perfectly.

Final assessment.

So is it worth it? I mean sure the loco was just $60 on eBay, but the decoder, harness, and speaker came to another $125. This makes the whole locomotive just under $200.

Financially, it's not that reasonable, you can find sound equipped locos for less (but they may have a weaker decoder), or for that matter more. The sound is fun - I wish it were better, but it is kind of cool to ring bells, and blow whistles. I also never realized how loud the train itself is, despite being on cork roadbed with a foam base, there is a lot of noise generated by simple train travel, and it drounds out the decoder at high speed.

More importantly, the loco runs 100% better and smoother with the Tsunami than the stock decoder that Bachmann puts in (not a complaint, just a statement). For instance, the Bachmann decoder would make the loco stutter at 128 steps; the Tsunami is smooth as glass, and the creap has been dramatically improved.

I would strongly urge folks to replace the Bachmann decoder with a better one, sound or no. For me, the sound is fun, does add to my enjoyment, and I think worth it.

Interested in what it sounds like? Here's a 4mb quicktime movie that is a good example.

'ere is dem nasty legal bits:

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