When I first decided to build a Z scale layout I knew I wanted to run a catenary line and a steam/diesel line but I assumed they would both be analog. I thought the concept of running Z scale locos with decoders was something out of science fiction. But then a little research on the internet and I found that there was a company providing drop in decoders for Marklin electric and diesel decoders so I was immediately hooked on the idea. After trying one out on one of my diesel locos, I could never go back. 


But what to do about my steam engines? There are no suppliers providing decoders made to fit specifically in Marklin steam engines but over the years both function and sound decoders have shrunk dramatically to the point where I was able to spend some time experimenting with them to see if I could get them to work with my trains. This is all still a work in progress for me but below are some photos of what I have accomplished over the last few years and how I did it.

First of all, the vendor I found many years ago providing drop in decoders for Marklin electric and diesel locos is Velmo run by a gentleman named Claudius Veit. Just go into the site, chose English unless you are fluent in German then go to Products > Cross Reference and you can look up the decoder you want by Marklin loco numbers. He even makes a few drop in sound decoders though they are mainly for modern equipment.

This is a Marklin 8880 diesel loco with the drop in decoder installed and it's original board below.These have basic functions which you can modify like consisting or acceleration/deceleration rates etc and light functions.

This next one is a Marklin 88131 "Ludmilla" diesel with a drop in sound decoder installed and it's original board below. In addition to many movement functions this also has a great set of sound functions like horns, brake squeal, engine noises and even a station announcement as long as you are modeling somewhere in Germany like am since it is in German. Notice the foam baffle on the right. When you put the shell back on, the foam seals the speaker to it so that you get the best possible;e sound out of it. Incidentally, Velmo decoders all come with comprehensive instructions (in German or English) on how to install the decoders as well as programming all the functions they offer.

The first steam loco I attempted putting a decoder in was the Marklin 8108 Oriental Express loco next below. 

For this one, I used a Digitrax 128ST decoder. I used a Dremel cut off wheel to remove some of the interior frame in order to fit the decoder.

Note that doing this reduces the weight of the loco and thereby also reduces it's pulling power as I found out the hard way seeing that I have some grades to deal with on my layout. You can find products like tungsten putty to place in the cab to help add some weight back but it's tricky. I'd love to hear your suggestions for adding weight to locos when there isn't much room to do so! It's tricky getting those wires to fit as well as soldering the bulb to a resistor and still having room for everything but it works!

After watching many Trainmasters TV videos featuring George Bogatiuk from Soundtraxx showing their sound decoders in HO locos and all that they can do, I was determined to find a way to get a sound decoder into at least a couple of my steam engines. At the time there weren't many "small" options so I bought a Soundtraxx TSU-1100 sound decoder for one of my Marklin steam locos that has a condenser tender which was just big enough (with a little bit of tooling) to fit the decoder, speaker and a capacitor to help a little with dirty track. See next photo.

The orange clay on the left was to try and keep the wires in place because one of the challenges (which I will go into more in my next blog) is keeping the wires from pulling the tender over in curves (again, more on that next time). In this next photo, you can see the wires running from the tender to the loco after being soldeed in place. On the layout, they really look just fine if they are black. Since decoder wires don't come in black, I just use a sharpie to color them.

The last set of photos shows installation of a Zimo decoder into a Marklin 88012 loco tender.

In order to gain access to the inside of the tender you need to very carefully lift the melted plastic edges of this half moon bit. Be sure to do it slowly as there is a tiny spring inside for the coupler and they disappear like magic if you're not paying attention.

The Zimo sound decoder.

Sugar cube speaker

Speaker from the side showing it's baffle purchased from Streamlined Backshop. I attached the speaker to the baffle with silicone for easy removal later if need be

Two capacitors wired in tandem to help with stay alive power for dirty track

Everything wired together. The white wire gets soldered to the LED headlight board. Note that to save space inside the tender I remove all unnecessary wires

Test fitting the whole shebang

Ready for install I wrap the decoder in caption tape to avoid shorts with the speaker

In the previous photo, notice how I ran the wires out the front wall of the tender. Here is a head on view.

And a side view of everything back together. I color the wires black after I solder to them to the engine since the colors tell me where they go.

Go to youtube to see a video of a completed Zimo sound decoder I installed in a Marklin 81371 Coal Transport loco. Just look up MARKLIN 81371 WITH SOUND DECODER. 

I will post a part "b" to this blog soon to talk more about how I install these and the challenges I found along the way and the ones I face now with the newer style of Marklin locos.

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