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Author Topic: Railbus DCC - lights and sound  (Read 6866 times)

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« on: October 22, 2008, 03:52:26 AM »

Hi all,

If you want to add sound to your On30 railbus the original Bachmann dcc-decoder must be removed.
The bus has many leds on it: frontlights, markerlights, lights inside. I counted 14 leds.
The decoder has to 'serve' them all what I think, draws more milliamps than we are used to with a regular locomotive with only headlights (and perhaps a cablight).

The following happens with my bus (a beauty, is not it ?).
With the Bachmann decoder all the lights work perfectly.
Not so when a (German Uhlenbrock) sounddecoder is installed.
The sound works perfectly. But with it only the two headlights of the bus on. You can shut these on/off. That is ok.
But no markerlights, no lights inside turn on.
The same thing with a standard ESU decoder.
The connections of the decoder are therefore 'proven ok' otherwise I would not have gained this result so far, isn't it? 

Any idea what causes the markerlights and inside lights not to light up with other decoders than with the original Bachmann ?

The original Bachmann decoderplug has two wee small resistors(?) mounted on it.
I have not seen this on dcc plugs before. The board even shows up some circuitry.
Has  this -parhaps-  anything to do with the 'challenge' I am facing with my bus?

Thanking you all for your kind replies!

John Baron
from Harderwijk
The Netherlands.

« Last Edit: October 24, 2008, 11:18:20 AM by Hobojohn » Logged

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« Reply #1 on: October 22, 2008, 12:08:31 PM »

I'm disappointed to hear of your problem with the lighting circuitry of the Bachmann On30 Railbus when used with the sound decoder. Since the Bachmann instruction sheet indicates that the lights are controlled by function 10 ("0") for on & off, AND also by function 1 for dimming, I wonder if this could be part of the problem, since most sound decoders are wired internally to use function 1 for one of the sounds (usually the bell). In our local club, we have noticed that out of two of the Railbus units we tried on our modular layout this past weekend, on one of them the lights would only flash on then off once when function 1 was set to turn them on, while the other unit worked just fine. The owner said both worked fine on his home layout which uses the Bachmann DCC system (our modules use Lenz). We are wondering if it's just a compatibility issue with Bachmann & Lenz.  Where are the DCC Standards when you really need them?

Also looking for answers,
Bill Nielsen
Oakland Park, FL USA
Florida On30 Renegades

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« Reply #2 on: October 22, 2008, 01:48:33 PM »

Thank you Bill,

Your remarks made me do another test: I have used another cab and another decoder, this time one without sound.
I used the Lenz LH 100 cab. Together with a Zimo decoder without sound "0" shuts the headlights on/of while "1" shuts the markerlights/interior lights on/off.

Like Bachmann promised.

The Uhlenbrock sounddecoder however uses "1" to shut of/on the sound and thus no markerlights etc.
Who is to blame? Mr. Uhlenbrock or Mr. Bachmann ?. I do not know the NMRA regulations on what "1" is intended for in the dcc-system.

Guess I have to go for an American made sounddecoder to solve this 'battle of the knobs"? 

Do you have any suggestions in this respect?

Thanks again
John Baron

« Last Edit: October 24, 2008, 11:18:51 AM by Hobojohn » Logged

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« Reply #3 on: October 22, 2008, 05:45:07 PM »

Hi John,

I'm glad to hear that you were able to get the light board to work with a different decoder. Now the issue becomes one of whether or not the sound decoder's function can be "re-mapped" via programming CV's to other function numbers, if any are available. This is getting beyond my knowledge level, I'm afraid. Perhaps some diligent reading of the sound unit's instructions will help. Another possibility would be to use a sound decoder that is meant to be used with a separate locomotive control decoder with multiple functions. To use the function 1 on your decoder, did you need to do any extra wiring or was it already wired with the DCC ready plug? Does your sound decoder have any extra function wires that don't go to the plug (I think most US  decoders use green & purple for extra functions)? Also what kind of plug is in the railbus, is it the typical NMRA style 8 pin plug, or a JST, or a different proprietary plug? Good luck, and keep us posted on any progress you make.

Bill Nielsen
Oakland Park, FL

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« Reply #4 on: October 23, 2008, 02:47:50 PM »

Hi Bill,

No solution yet.
I did not make any modifications to the electrical system of the bus.
There is a standard 8 pin plug (NMRA 652)
The F1 's keep competing with each other.
I have asked the soundchip producer whether remapping is possible.
No notification yet.
I have to wait for someone to come up with a solution, I guess.
A different decoder? I do not know yet

This is the sound I choose with Uhlenbrock Germany
Hope you can try it out on this link:

Choose: Produkte
Choose: Digital
Choose: sound
Choose: Probehören

choose on that page the following (scroll down on the page) :

historischer Triebwagen TCA der SKLGB

Thought it would go fine with the Bachmann bus. Hope I can stay with it and get the lights to go on with it.

Hope you have fun listening.

Untill then
John Baron
The Netherlands.
« Last Edit: October 24, 2008, 11:19:18 AM by Hobojohn » Logged

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« Reply #5 on: October 24, 2008, 01:59:32 AM »

Here's what's going on based on my examination of the Bachmann decoder and it's associated plug on my Railbus.

The lights are non-directional.  This is not the decoder.  It's the plug.  The front headlights are cross wired to both the white and yellow decoder wires on the plug.  Further, the marker & interior lights are cross wired to the headlight power (again on the plug) and that power feed goes into the Railbus on the Green function socket point.

The net result is that all lights are on (or off) based on F0 with the factory decoder. 

With an after market decoder, you will need at least 3 functions (white/yellow/green) to light up all the lights.  Since decoders tend to come in 2, 4 and 6 functions, you'll need at least a 4 function decoder.  Getting the lights set for non-directional behavior with an after market decoder's standard plug is just a programming exercise.  If you substitute the plug from the Bachmann factory decoder coupled with a 2 function decoder, you'd end up with the same effect as the stock decoder.  This, however, will require some fiddly unsoldering and re-soldering of the Bachmann plug board.

Hope this is helpful.


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« Reply #6 on: October 24, 2008, 05:00:35 AM »


Your explanation (and Bill's as a start) turned out to be the solution to the problem
Thank you ! It got me going.

Here it goes:

When using another decoder with the 8-pin plug (Nem/NMRA 652) make sure the green function wire (F1) is soldered to the empty pin on the plug and that this wire is also connected to to the decoder.  With European decoders the green wire is many times not soldered to the pin.
Many decoders have the green wire already connected to the decoder, mine however did not.  But there was a solderpad provided on the decoder for it. It is a bit of a tedious job but a fine pointed soldering iron (max 15Watt) should help you out.

When hooked up to the socket on the bus next, the F0 turns on the headlights, F1 turns on the markerlights and interiorlights. Both stay on non directional. Leave that.
((Sorry Bachmann, you have not done anything wrong, just made it a bit confusing. )

Next, I hooked up the sound decoder through a susi plug.  And of course F1 showed  'the battle' mentioned before.
I had to do some remapping of the function buttons next. For this you have to follow the instructions that go with the sounddecoder.
I left F1 to handle the markerlights, F2 and others were adressed to the soundfunctions.
I used the Lenz LH 100 to do this programming.
It can be done!

Dear Mr. Bachmann, what do you think of all this ?

Bachmann, our much appreciated On30 manufacturer, should (have) understand/forseen this and should have written about it in the instructions, I would say. 

Narrow gauge greetings to all of you,
John Baron

« Last Edit: October 24, 2008, 11:19:43 AM by Hobojohn » Logged

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« Reply #7 on: October 24, 2008, 02:06:49 PM »


Do you mean that you are using a decoder that has an additional plug (susi) built in for adding a separate sound board, or did you remove the original decoder that you attached the green wire to and replace it with an all-in-one sound decoder (and did IT have the green wire attached to the plug, or did you have to add this on the sound unit as well)?

Bill Nielsen
Oakland Park, FL USA

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« Reply #8 on: October 24, 2008, 03:12:31 PM »

Hello Bill,

This is what I did:
I am using a decoder that has an additional plug (susi) built in for adding a separate sound board.
It is a also a seperate soundchip.
Check out this (usa) internetadress:

You can see the (motor) decoder on this picture  From the soundchip only the plug and the wire. On the motordecoder the susi plug is fitted (for 4 small wires) But it is for the impression only. The soundchip itself is as large as the motordecoder.

I have a soundadapter and with it and my PC and through the Susi plug I can load in as many different sounds as I want. I have used a very small soundchip and decoder. It all fits nicely under the roof of the railbus where there is litte space.
The only thing I am waiting for is a small 14mm speaker I ordered today in your country with John Thut of DCC hobby supply. It takes a week to get down here in the Netherlands. They are not available here.
Then I will be all done with this railbus and it can go into service.
I am happy with it now.

John Baron

« Last Edit: October 24, 2008, 03:14:31 PM by Hobojohn » Logged

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« Reply #9 on: October 24, 2008, 05:23:02 PM »

Thanks John,
I think I understand now, but the only thing I'm not sure of from looking at the picture in your link, is where is the green wire (or its attachment pad)? A 14mm speaker seems a bit small, given the size of the railbus. Was the limiting factor here the required height or thickness of the speaker, in order to keep it out of sight up in the roof? Glad to hear you seem to have it under control.

Bill Nielsen
Oakland Park, FL USA

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« Reply #10 on: October 24, 2008, 05:52:31 PM »

John -

I'm glad to hear that my info was of some help.

-John Roth
Yosemite Short Line
California Central Coast

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« Reply #11 on: November 03, 2008, 05:46:09 PM »

Hi all,

I have another tip for you on  the speaker.
There is not much room under the roof for a decent speaker. There is lots of room though inside the truck The truck body can be taken of fairly easy. It is 'snapfitted' onto the frame.

Hold the front end of the frame in your left/right hand, and the body in your right/left hand.  Wiggle the body a bit and it should come up. The sides and back-end come lose just by bending the body carefully a bit towards the outside and pushing the frame up the same time (your bus lays on its top) 
With a piece of double sided tape I mounted the speaker to the inside of the roof.
About in the middle where there is a whole. There it is least visible and you do not have to interfere with the leds for the inside lighting.
The speakerwires go through two of the the many holes on the intended place for a speaker.
Solder the wires on to your sounddecoder, clean/insulate the soldering point, add the roof again and away goes your bus .
Taking the body off  is also great for adding passengers to your truck as well.
(At least you get some much needed revenues for your railroadcompany that way....)
I have not tried the trailer yet, but I assume it opens the same way.

Happy railroading!
John Baron
The Netherlands. 
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