Wiring to Decoder for LGB 18V Smokestack in 2020D

[fairflixt]

Hi everyone,

I've decided to enter the DCC world and am converting my first loco, a 2020D Stainz from the Circus starter set that kicked off my g-scale journey.

So far, things have been going OK but I got stuck on the wiring for the smokestack. This age/version of the Stainz has the 3-lead motor block and the smokestack is the type that goes all the way through the boiler to the bottom of the loco and has the on/off switch underneath (LGB 65103). The original connection is through wires that run the length of the motor block and connect the pickups and wheels. Electrical connections are made with a copper strip and the switch at the bottom so no exposed wiring to use for color guidance or as any other clue.

My question: Is there a directionality that I need to connect this to the decoder? In other words, does Dec+ have to go to a specific lead i.e. the copper strip along the shaft of the smoker or the bottom connection where the switch is, or is it irrelevant? If I understand how the smoker works, a big resistor immersed in the oil that gets hot from current passing through, I would guess that the direction doesn't matter but without positive confirmation I'd prefer not rely on my layperson's understanding.

I've tried searching the forums but was unable to find a specific answer.

Thanks,
Vincent

 

[PhilP]

Hello Vincent,

You are correct, in that polarity does not matter.

You may need to alter the CV that controls the voltage for the output you are using for the smoke output. - I would start with a value of 20, and see how it goes.

Enjoy!

PhilP

 

[fairflixt]

Hello Vincent,

You are correct, in that polarity does not matter.

You may need to alter the CV that controls the voltage for the output you are using for the smoke output. - I would start with a value of 20, and see how it goes.

Enjoy!

PhilP

Thanks Phil, just what I needed to hear! Also thanks for the CV suggestion, will speed up the programming process if I ever get the wiring finished

 

[Dan]

When I did this I asked myself how often will run smoke. Not very often is my answer so I added a resistor in series with the smoke power, and just use the lever on the bottom of the engine to turn it on and off. Here is the fun part for some...What voltage do you have on your track?? Many systems have less than 24 volts, exception is the Zimo which does feed 24 volts to the rails and I used a resistor that allowed me to drop 6 volts to the smoke unit. NCE here in the USA has a 24 volt supply but less than 21 volts gets to the rails. Mts has a 24 volt supply and gets 22 volts to the rails. ZImo has a 30 volt supply to get 24 volts to the rails. So, most speed control units (DC and DCC) drop 2 to 3 volts to the rails from their power source. I use the zimo HO decoders in my engines and keep the smoke current from heating up the decoders with my method.

 

[LGB333]

You don't indicate what DCC system or DCC brand decoder or whether sound or no sound. To echo Dan's post, unless you're using Zimo with its high voltage output, you won't normally need to dim-down the output voltage on the decoder for the LGB 18 volts smoker.......they can handle 18 - 20 volts. I use both a Massoth DCC system and an ESU DCC system and they put out 20 volts to the track, and again as Dan indicates, the output on most large scale DCC decoders drops about 1 - 1.5 volts so the 18 volt smoker then receives about 18 - 19 volts. On Massoth DCC decoders, the default setting on output terminals is 32, full track power, and you can leave it at that.

If you do install a DCC sound decoder, the photo below shows the speakers I install into the Stainz cab face down on the right, inside cab wall......produces excellent sound. You can get these China-made, 3 Watt speakers, that will handle both 4 and 8 Ohms, on eBay. I paint the speaker's metal frame flat black for better appearance than the bare metal.

Good luck on your conversion, and you're in luck that your older LGB Stainz isn't their first motor block design, the infamous "clam shell" shown below that I did recently.

 

[fairflixt]

Dear Dan and Tom,

Appreciate the further replies. This has been a budget and learning project. As such, I've assembled a command station from an Arduino and some motor boards powered with 24V and running DCC-EX. The decoder is from MD-Electronics, the mXion type which included a separate sound board. I bought it as a set with a speaker which I actually mounted in the same place you did as well! I'm also happy to see my decoder install in the tender looked similarly full if not as clean and I made my life a lot more difficult with the order that everything was put in place...

All of this is partly an electronics learning exercise, hence the lower spending budget but then it doesn't hurt as much if I make something go poof.

For now, I have programmed the relative CV to 75% which equals 18V if there were no voltage drops from CS to decoder to smoke unit. Seems like a safe place to start and then I can always increase as I get more comfortable.

On that note, I had one more question about the switch at the bottom of the smokestack. On reassembly, do I need to avoid connection of the switch with the nut? It would seem the nut is connected to the smoker shaft which is one of the poles and hence only the brass circle in the bottom of the smoker should make contact with the switch. At the moment the bend in the switch contacts the nut and does not contact the brass circle at all (see pictures). Can this short something out?

Thanks as always!
Vince

 

[PhilP]

You are correct, it should only contact the 'pip' in the centre. - It would be better if the 'switching' part was the other way up.

PhilP

 

[fairflixt]

You are correct, it should only contact the 'pip' in the centre. - It would be better if the 'switching' part was the other way up.

PhilP

Thanks, that's what I was afraid of!

 

[fairflixt]

I flipped the switch to go the other way but then it hangs down too low and will happily catch on anything in between your rails (I guess those LGB designers did put some thought into their design ). So I returned it to the original position and bent the pin a little bit to avoid contact with the nut. I tested it and this works great with the voltage set to 75% by CV.