Deferred maintenance

Very prototypical.

Frame of mind

Not that it's any help to you but allow me to commiserate. I definitely relate to requiring a certain mental state before I start digging around and soldering inside a model locomotive.

Once I do get started it's touch and go. If the disassembly and first wires go fairly well then success tends to breed success. If it's wobbly right off, then it just keeps going downhill and has to be put away for another day.

Good luck.

Yep, I'm in that boat with

Yep, I'm in that boat with you and Kent. I have to be in the right frame of mind or I start wanting to throw hot soldering irons at people.

And this is why some people

And this is why some people keep a Beater Blue Box SW-7 around.

Being in N, it's some Beater Bachmann Dash-8's.

Front row are first Gen B'mann's, next two row's 2nd Gen, third are Atlas which I should have bought in the first place. Strangely, they all MU pretty well together. (shrug)

Steam Locomotive Drawbar/Connection Problems

Bachmann locomotives are strictly PITA in the area of tender electrical connections. And they don't use the NMRA wire color code for DCC wiring either.  I have one of the Bachmann ALCO 2-6-0's in my future projects box.  Unfortunately I am trying to stick to prototype for my Southern Pacific Port Costa Layout.

There are some published wiring guides illustrated for the Bachmann locomotives if you search deep enough on the internet. I think I found one for the 2-8-0 on a YouTube video.  From what I remember for the 2-8-0 off hand, the two prong receptacle is for the power pickups from the loco.  The 4 prong receptacle is for the motor leads and lights from the decoder back to the locomotive.   You may find a similar YouTube for rewiring the 2-6-0. If you are like me, I hate wiring specially with tiny wires that need minimal solder in heat sensitive plastic. 

Thusly, I have been using the Mehano 2-6-0 which closely resembles an SP M-4 2-6-0.  I have had to rewire them completely for DCC (I think it predates the standard but did use red/black for pickup wires) using small auto parts connectors and also use a Nix Trainz Decoder Buddy in the tender just so I could get correct keep alive solder pads. 

The one operational  Mehano 2-6-0 will likely be my test bed for the new LocoFi Generation 3 WIFI receiver module which is due in a couple of months which fortunately uses the NMRA wire color codes.  The new module will include steam sound capability if someone records a compatible steam program which can be loaded onto a micro SD card as the module contains a card slot.  

The Tender

Here's a picture. I've disassembled this as far down as I want, I'm reluctant to go further until I have the other plug/harness and am ready to do the job. I have yet to find a wiring diagram online.

I'll be danged if I can figure out where eight wires are going to go. Assuming two wires for the speaker and two for the light, then you only have six connections left. From the loco side of things it would be six wires also, light, motor and rail pickups. At any rate, I can't worry myself anymore over it than I have today. I've been pretty bummed out but it's time to put it aside till our slow moving mail gets the replacement plug/harness here. I need to figure out where I put my Climax so I can attempt to fix it and get myself going on the RS-1 decoder install which is something I should have already gotten to.

As Dave said, "deferred maintenance" and my procrastination has come back to bite me. I'm also apparently a prototype modeler and didn't know it!

. . .

Michael.

This is the same as the new released  TUS-BH2 sound decoders from Soundtraxx. This is a true Tsu2 replacement for the Bachmann decoder you have.. The wiring is the same

Install guide :  Find the chapter re BH2.

https://soundtraxx.com/content/Reference/Manuals/Tsunami2/Installation-Guide.pdf

There is other documentation  also

https://soundtraxx.com/content/Reference/Documentation/Technical-Notes/Tech_note29.pdf

https://soundtraxx.com/products/tsunami2-digital-sound-decoders/tsu-BH2/

Marc

Looks like six wires in the plug

You cant really hurt the loco, if the decoder is in the tender.  
 

An ohmmeter to map things and then an old DC  power pack, or better a power supply, and a sewing needle put in the pins will quickly confirm the wiring into the loco.  Two to headlight, two to rails, two to motor ….  The might or might not be in pairs on plug.

With  the schematic in hand, you can likely trace the wires and then just snip them one at a time, slip on some heat shrink tubing and solder to matching wire on your new plug paying careful attention to the plug orientation (pin 1 is often marked).

The longer wires won’t hurt and you’ll quickly spot if your drawbar is unhooked as your and tender spacing will be obvious even from a distance. 

Me, I’d just cut the plugs out altogether and join the wires with more wire of equal gauge. 

Actually, I was wrong

There are enough places for eight wires to go...I did some tracing with my multi meter and came up with the diagram below which seems to jibe with what Marc has posted. The broken wires would appear to have been from pins 5 and 7 on my diagram. It should be easy enough to figure out once I get the new plug and harness. That Soundtraxx info should be helpful as well. Maybe someday I can upgrade from the stock decoder to one of those but for now I'm just hopeful to get my  loco running again. I really love this little loco for the price and I wish they'd do another run.