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Wire Diagram for Lighting up a Dummy Locomotive

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Wire Diagram for Lighting up a Dummy Locomotive
Posted by Missouri Pacific BNSF on Thursday, October 3, 2013 10:11 AM

Does anyone have a wire diagram for how to wire up lights for a dummy locomotive?  I had an Athearn Genesis SD70ACE completely blow up and fry on me and I am just going to make it a dummy instead of replacing the board and decoder but I want lights; how do I do that?  Thanks.

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Posted by Train Modeler on Thursday, October 3, 2013 1:50 PM

If you want to use DCC, then just get a good function decoder and wire it in per the instructions.   TCS makes a good one.   This one is 4 function, of course you can add another if you wish.

http://www.tcsdcc.com/Customer_Content/Products/Decoders/HO-Scale/FunctionOnly/Function%20Only.htm

Richard

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Posted by mlehman on Thursday, October 3, 2013 2:42 PM

Even easier and cheaper? Wire it as a half-wave circuit. Take power from the rail on one side, use a resistor to protect the LED as always and then wire to the other rail. I think this can also can be used to make the lighting directional, depending on which rail you draw positive from, but it's been a few years. No decoder needed.

I have a Walthers wedge snowplow wired this way.

You can also wire a switch into the circuit of you want to be able to turn it off.

Heck, with a loco, you don't even have to worry about arranging for the electrical pickups. They're pre-installed if you're starting with a formerly powered unit.

Mike Lehman

Urbana, IL

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Posted by Texas Zepher on Thursday, October 3, 2013 5:20 PM

Missouri Pacific BNSF
Does anyone have a wire diagram for how to wire up lights for a dummy locomotive?  I had an Athearn Genesis SD70ACE completely blow up and fry on me and I am just going to make it a dummy instead of replacing the board and decoder but I want lights; how do I do that?

??? Are you certain the lights didn't blow also? 

Generally put one sided of the track power to the lights. Put the other side of track power to a resistor appropriate for the lamp.  Connect the other side of the lamp and the other side of the resistor together.

Determine the resistor size by applying ohms law to the track voltage your DCC system is set to and the current draw of the lamp.   R=E/I

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Posted by steemtrayn on Thursday, October 3, 2013 10:49 PM

If you always run the dummy with a powered loco, you can run the rear headlight wire from the powered loco to the front headlight of the dummy.

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Posted by hon30critter on Thursday, October 3, 2013 11:33 PM

Tony's Train Exchange lists a Digitrax TF4 for $17.95:

http://tonystrains.com/products/digitrax_decs_med.htm

Four functions gives you lots of options like step lights, number boards etc.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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Posted by Mark R. on Friday, October 4, 2013 1:18 AM

Wiring the lights to the track through a resistor is a cheap way out, but .... the lights will be on all the time with no control over them.

I would be more tempted to go with the accessory decoder. Address it to the locomotive like a regular decoder, pull up that address and turn on / off the lights when you want.

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

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Posted by zstripe on Friday, October 4, 2013 1:34 AM

MP BNSF,

I think maybe a little interaction, on your part is necessary,,,Do you know how to take the shell off? How to remove the motor and drive line? How to remove the light bulbs,,which are probably burnt out?How to remove the decoder? Is it an HO scale SD70ACE??   Those questions,would help others,help You..Just My My 2 Cents

Cheers,Drinks

Frank

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Posted by richhotrain on Friday, October 4, 2013 3:42 AM

If you fried the decoder, why don't you just replace it?

Why turn an otherwise working loco into a dummy?

What kind of decoder is it?

Rich

Alton Junction

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Posted by Missouri Pacific BNSF on Friday, October 4, 2013 8:18 AM

 

It is an Athearn Genesis HO scale SD70ACE.  I do know how to take the shell off, the lights are burnt out, and at this point, I think I plan on buying the accessory decoder and installing it.  Will it come with the lights, resistors, everything needed to run all lighting function or do I have to buy those items separately?

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Posted by Missouri Pacific BNSF on Friday, October 4, 2013 8:22 AM

The entire circuit board is fried, no just the decoder, otherwise I would replace it.  I have removed the gears and the motor, added weight disconnected the existing lighting, I just need to put everything as far as lighting goes back in and that is where I am unfamiliar.

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Posted by Missouri Pacific BNSF on Friday, October 4, 2013 8:29 AM

How does the accessory decoder get wired to the locomotive?  With my circuit board shot, do I just draw power for the decoder from the trucks?

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Posted by zstripe on Friday, October 4, 2013 8:34 AM

MP BNSF,

The two links given above, should help and here is another,,hopefully the link works:

http://www.ulrichmodels.biz/servlet/the-615/Athearn-SD70ACe-LED-Lighting/Detail

Cheers,

Frank

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Posted by mlehman on Friday, October 4, 2013 8:38 AM

Mark R.
Wiring the lights to the track through a resistor is a cheap way out, but .... the lights will be on all the time with no control over them.

True, but it doesn't snow all that often, so no big deal about it being turned on fulltime on the plow.

If I was going to  do a loco like this, I would wire up the number boards only. IIRC, since you can wire this circut as directional, you could wire the headlight to be on only when the unit was running "forward" in a consist, as when backing up. I presume it wouldn't ordinarily be a lead unit.

Then there's the suggested on-off switch.

I agree, a decoder gives a lot more flexibility, even if for lights only. Sometimes you're on a budget and there's no reason not to have lights if you have the LEDs and resistors.

Mike Lehman

Urbana, IL

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Posted by zstripe on Friday, October 4, 2013 8:45 AM

Missouri Pacific BNSF

How does the accessory decoder get wired to the locomotive?  With my circuit board shot, do I just draw power for the decoder from the trucks?

Yes,,that's how the decoder gets it's power to begin with.

Cheers,

Frank

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Posted by cedarwoodron on Friday, October 4, 2013 9:54 AM
I have wired a positive to negative 3mm LED (with 470 ohm resistor)for forward lighting and inverted that arrangement (negative to positive) for rearward (movement) lighting. No bridge diode rectifier needed, as long as both wheelsets are getting current from the track. That works on a DC track, as far as I have been doing. Others may comment regarding this simple arrangement for DCC (maybe a larger resistor value???). cedarwoodron
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Posted by zstripe on Friday, October 4, 2013 11:25 AM

Your way is fine for DC..on DCC,the track polarity,does not change,the decoder does that,to change motor direction..and would use a higher rated resister so the LED's won't be so bright,because of the constant voltage to the track..

Cheers,

Frank

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Posted by mlehman on Friday, October 4, 2013 1:05 PM

cedarwoodron
Others may comment regarding this simple arrangement for DCC (maybe a larger resistor value???).

The 470 ohm sounds a little low for DCC. I tend to use more resistance anyway, just to tone down the laser-like characteristics of LEDs. I probably used 1k or higher resisters in the snowplow, but I'm pretty certain so long as you're using something higher than 470 is going to be OK. I actually don't think 470 is bad, it just doesn't leave much slack. I always like more slack in my lighting circuitsClown

IIRC, the trick to getting light in both directions with these circuits is to run one side to one rail and the other to the other rail. That's "half" of a full wave bridge, thus the term "half-wave". But I get confused about electrickery easily, so verify the circuit we're discussing at one of the handy DCC sites.

Mike Lehman

Urbana, IL

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Posted by MisterBeasley on Friday, October 4, 2013 2:48 PM

Is this a DCC locomotive that you are running on DC?  Or are you running DCC on your railroad?  The answer will change the value of some of the suggestions.

Also, am I the only one who wants to know how you fried the electronics?  If it were me, I'd want to solve that problem pretty definitively before putting more components on board.

How is the motor?  I know you say you removed it, but was that necessary?  On most locomotives, you don't need a "circuit board" at all.  The decoder does the work.  The board is mostly just a convenient place to plug in the decoder and leds without soldering.  Sometimes there are resistors for lighting, but many decoders have them built-in, too.

It takes an iron man to play with a toy iron horse. 

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Posted by zstripe on Friday, October 4, 2013 4:54 PM

Mike,

Cedarwoodron,is using the 470 resistor for DC lights,which is fine,,,unless of course he run's at full throttle,all the time..

Cheers, Drinks

Frank

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Posted by Texas Zepher on Friday, October 4, 2013 8:11 PM

Missouri Pacific BNSF
I think I plan on buying the accessory decoder and installing it.

This is what I don't understand. Accessory decoders are often big and bulky.  They are going to be just as hard maybe harder to install.  There isn't a huge difference in price.     Why not just take out all the fried components and put in a regular decoder designed for this task.  I'm thinking of the NCE DA-SR or Digitrax DH165A0, DH165K0 decoders?

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Posted by Mark R. on Friday, October 4, 2013 8:44 PM

Texas Zepher

Missouri Pacific BNSF
I think I plan on buying the accessory decoder and installing it.

This is what I don't understand. Accessory decoders are often big and bulky.  They are going to be just as hard maybe harder to install.  There isn't a huge difference in price.     Why not just take out all the fried components and put in a regular decoder designed for this task.  I'm thinking of the NCE DA-SR or Digitrax DH165A0, DH165K0 decoders?

Case of miswording .... should have said "function only" decoder as opposed to "accessory" decoder ....

Mark.

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Posted by richhotrain on Saturday, October 5, 2013 4:22 AM

Texas Zepher

Missouri Pacific BNSF
I think I plan on buying the accessory decoder and installing it.

This is what I don't understand. Accessory decoders are often big and bulky.  They are going to be just as hard maybe harder to install.  There isn't a huge difference in price.     Why not just take out all the fried components and put in a regular decoder designed for this task.  I'm thinking of the NCE DA-SR or Digitrax DH165A0, DH165K0 decoders?

I agree with you, TZ.

If the OP fried the DCC Ready circuit board in addition to the decoder, just replace them both instead of destroying an otherwise perfectly good locomotive.

Rich

Alton Junction

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Posted by cedarwoodron on Sunday, October 6, 2013 9:14 AM
That's why I ordered some 1K ohm resistors in my last China purchase, and am using them now, more so than the 470's. The 470's are still good for structure lighting, where you want to illuminate a large open area (warehouse interior, etc.). Taming the brightness with a lightly translucent coating (highlighting pens, also lowers/diminishes the intensity. Cedarwoodron

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