Got a stumper for you.....


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Kedric

New Member
Hello everyone,

I got a question for you all that about 2 months of intrawebz surfing hasn't come up with an answer for me. I have been almost dead set on DC for my layout I plan on building and am getting close to the bench construction phase. The design is down, and I've been buying locomotives + rolling stock for awhile whenever I see a good deal. Here's the catch though, I have toyed around the idea of going DCC and installing decoders but haven't because of 1 engine I really want to run on it. My DD40X in PRR colors I plan on using for the coal drag (main feature of my layout) is still the DC variety. I have yet to see how to wire up the twin motor assembly with a single decoder.

The only idea I've come up with is, removing the connecting drive shaft between the motors, electrically isolating them from each other, installing TWO decoders, 1 to each motor assembly and then programming them to act like two different engines but have matching speed settings to keep the whole thing from dragging or pushing the truck wheels on either side of the chassis. Anyone else have experience in this that could enlighten me as to if this would work, or should be avoided? I was told by my hobby store train guy to just put it on display if I liked it that much. Well I do want to display it...as it's pulling a 15 car coal line through my fictitious setting, not sitting pretty in a cabinet. I may get to that day one day, but I am wanting to do it also for the challenge of making it happen.

It's really only thing holding me back from going to DCC. I don't want to automate my layout too much but having lights, sounds and ability to do wireless control would be ideal since I enjoy switching and spotting cars more so than following a train through scenery and according to my Anyrail program, I have 403' of total track to run on so ability to move freely without back and forth to a stationary cab is making me re-think my hardline DC approach.
 
No need for all of that, just use one decoder and wire both motors to the one decoder in parallel. You just need to make sure the decoder can handle the current of both motors together.
 
Both digitrax and tcs have info on their sites about converting these to DCC.




Sent from my Vic20 using Java Moose
 
The only reason I can see where a single, higher-amp decoder may not work, is if the DD40 has the old black iron ring "jet" motors. If it does, you would need to replace them anyway.
 
I have two DD40X's (both UP) .. one is DCC dual motor and one is DC unknown .. this thread has me curious about taking it apart and maybe adding a decoder
 
Glenn, there is more than one model and manufacturer of DD40. Athearn makes two different versions, and several variations, and Bachmann makes at least three versions.
 
The DC version is a Bachmann (made in Hong Kong) single motor, two white bulbs, one yellow bulb. I've already put it back together and probably WON'T spend the $20+/- to add a decoder. The Athearn DCC dual-motor is fine for me.
 
It sounds like the old athearn. You have to separate the motor(s) from pickup from the frame to isolate them You really may be better to switch them to cans anyways if your going to do that. I own a Westside Triplex, its 3 decoders for sound. It has 3 motors. It works fine. The issue is back EMF (BEMF) as it uses the motor as a generator. The decoder switches fast between power and generator to get data from the motor how fast its going and its powering. using this trickery the decoder on steam engines like the QSI Titan will calculate chuff sync perfectly using no cams. Other decoders you try to sync timing for chuff, not on the titan. perfect. Always. Putting 2 motors on a decoder I wonder how this messes the BEMF. I'd go for 2 decoders and sound both for the 2 engines in them, just sync the sound off slightly so they don't razzle perfectly pitchy. I find myself tweaking the sound speed on multiple engines so they dont "cancel" each other out.
 
Kedric said:
I have yet to see how to wire up the twin motor assembly with a single decoder.
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I don't understand the issue. Why can't you get a high current decoder and wire them in parallel? The PCM diesel AB units work like this. There is a decoder in the A, which is wired to a second motor in the B unit. I wired several Stewart AB units that way. Just because they aren't in the same frame should not make any difference.
 
To use a single decoder for both motors, wire the two bottom contacts of the motors to each other by soldering a wire to them. Make sure the little contact tabs are either bent out of the way, or cut off, so you will not have a short. Then solder a single wire between the two top contacts of the motors. Then, solder the (in most cases) orange wire from the decoder to the bottom and the grey wire from the decoder to the top wire. Attach the red and black wires from the decoder to the frame contact and truck contact, and you are done. After you make sure it works, you can wire up some LEDs to the blue, yellow and white wires.
 
bnsf971 said:
To use a single decoder for both motors, wire the two bottom contacts of the motors to each other by soldering a wire to them. Make sure the little contact tabs are either bent out of the way, or cut off, so you will not have a short. Then solder a single wire between the two top contacts of the motors. Then, solder the (in most cases) orange wire from the decoder to the bottom and the grey wire from the decoder to the top wire. Attach the red and black wires from the decoder to the frame contact and truck contact, and you are done. After you make sure it works, you can wire up some LEDs to the blue, yellow and white wires.
Click to expand...

That's what I needed to know, thank you!.

Iron Horseman, I said " I have yet to see how to wire up the twin motor assembly" as in I have yet to see a wiring diagram or it explained. I didn't say it's not possible. I just couldn't find the answer myself.
Thank you all.
 
Kedric said:
Iron Horseman, I said " I have yet to see how to wire up the twin motor assembly" as in I have yet to see a wiring diagram or it explained. I didn't say it's not possible. I just couldn't find the answer myself.
Click to expand...
Ah, I miss understood you that were asking how.
 
Yeah, I'm new to the hobby and I only am vaguely familiar with DC so this is all foreign to me. I did get a basic oval like I had when I was a kid setup in the basement on the concrete to test out my soldering skills and track work. I got one of my old hand-me-down engines from my Dad when he was a kid to run laps for awhile and even a few cars behind it for a bit too. It's not too bad for not being nailed down, and only roughly soldered together in dim lighting. Next step will be running some lighting and what not down there. Still pulling out the old tube and post wiring in a few places down there. The majority of electrical was updated but in a few spots it looks like they just left it hanging still hooked up to a breaker....which will need to come out before I go installing benchwork and electrical runs for the lighting.
 
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