USRA 2-8-2 Light Wiring

[mkingery]

I recently purchased a USRA Light Southern 4501 DCC ready loco (54403) and will be installing a Soundtraxx TSU2 decoder.  I wanted to make sure I understand the wiring at the existing circuit board.  Especially the B+ and B- connections which I can guess what it might be, and then be wrong.  So here is what I assume about the wiring from the Engine to the Tender.

R = Right Rail
M+ = Motor
L- = Headlight Common
B+ = ??
L+ = Headlight Positive
B- = ??
M- = Motor
L = Left Rail

I would appreciate any corrections and filling in the blanks nad the B+/B-.  Thanks, Mike

[rich1998]

It has been some years since I bought HO Bachmann DCC steamers. Bachmann changed the labels I see.
My steamers had slightly different labels for lighting.
I think the Common was a positive voltage and the Front and Rear lights both negative connection.
Guessing, Com, Fl, Rl labels. I did some wiring.

Cannot find the PC boards right now. All other labels the same.

Probably no help.

Rich

[Len]

On some Bachmann boards you'll find some, or all, of these markings:

R:    Right Rail
L:    Left Rail
M+: Motor Brush Connected to Right Rail
M-:  Motor Brush Connected to Left Rail
L+:  Light Positive
L-:   Light Negative
B+: Battery Positive*
B-: Battery Negative*

*Some boards allow the addition of a reed switch On/Off controlled battery pack for operation, rather than using track power.

Len

[jonathan]

I have the sound value USRA Light 2-8-2, not the DCC ready version.  So forgive me if I get this wrong.

When I have installed Soundtraxx TSU anything in a DCC ready Bachmann loco, I always obtain the 8-pin plug harness to connect to the sound decoder.  The advantage, for me, is not having to worry about how the loco board is wired.  As long as I get the color coding matched on the harness, and orient the plug correctly upon connection, all is well.  Just saying...

I believe all the Bachmann USRA Light Mikados come with a reverse light. Mine did. You may see some marking on the board like "RL+" or the like.  That might help clear things up a bit.

Do you plan to remove the loco board and hardwire? Or plug into the board socket?  I have always gone with the socket. I digress.

Regards,

Jonathan

[Trainman203]

That's the same tender as the 2-8-0 except for having the nice bright reverse light.  I wish the 2-8-0 came with that tender and the mikado's nice bright big sunbeam headlight.

[mkingery]

Len,

Thanks.  Interesting on the B+/-.  I was trying to invent things it could be, that was not one I came up with.

Johnathan,

Understand on the 8 or 9 pin decoder.  I just like to do it a different way.  Keep a bit of a standard method to the madness of collecting locos, and doing the installs myself.  Good that we have options.

And yes it does have the Rear Light.  That pair is wired directly to the mother board in the Tender.

I going to use a NixTrainz Decoder Buddy and a TSU2 21PNEM decoder.  I have a low end 3D printer so I can make up some mounting feet for the new motherboard without to much trouble.  Looking forward to adding the 4501 to the 630 I have, both of which are at the Tennessee Valley Railroad Museum in Chattanooga, TN.  Either in service or rebuild.  The Southern (ex Army) 610 is also there.  I was lucky enough to get a cab ride in the 610 years ago.  That was an experience for sure.

Stay safe all,
Mike

[bapguy]

I say the B+/B- is for the rear light on the tender.    Joe

[Len]

I say the B+/B- is for the rear light on the tender.    Joe

Nope. They actually get used by large scale operators who use batteries instead of track power.

Len

[jonathan]

I had to look up the Decoder Buddy. Had never heard of it. That's taking your DCC very seriously... replacing motherboards. Great stuff.

Since you're going the extra mile on the electronics, may I suggest something? The Bachmann Light Mikados really benefit from some balancing. If memory serves, I recall adding some weight up front to get the center of gravity between the 2nd and 3rd set of drivers. Made a big difference in tracking and pulling.

Perhaps you've already thought of that.

Regards,

Jonathan

[mkingery]

Johnathan,

Thanks for the tip on the balancing.  I will check that out.

I do carry the decoder/control/sound to an extreme.  But I enjoy that part, and it fits what I have experience with.  So many areas to explore and options with this hobby.

Mike