This installation of TCS MB2 Motherboard, WOW121 Decoder, and 28mm WOWSpeaker is for the HO Scale Bachmann Heavy 4-8-2.
First unplug the tender from the locomotive and set the engine aside. Next remove the screw identified below in yellow from the bottom of the tender.
With the tender screw removed you can tip the shell from the front to the back (to slip the rear plastic tabs out) and lift it off the chassis. You should now be presented with something similar to what you see below.
This is as good a time as any to point out that there seems to be no standardization of wire colors in Bachmann steam engines. Do not use the colors of the wires on the original board as your wiring guide. The first pad in the upper left is the ORANGE wire (motor +), and the pad directly below it is the GREY wire (motor -). Moving directly down we find two RED wire (track +) pads in a row followed by two BLACK wire (Track -) pads. The last two pads are the WHITE wire (forward light -) and the BLUE (+12...
Once you have attached all the wires you can unscrew the two screws in the original lighting board (highlighted in yellow above) and using them to screw the MB2 into place.
Now it's time to move on to the speaker. As you can see there is already a speaker mounting location built into this shell for 28mm round speakers. We will use this to mount our 28mm Round TCS WOWSpeaker with hot glue. Simply place the speaker into the recess in the frame, glue all the way around the outer edge and solder two wires from the speaker to the SPKR pads on the MB2. Speakers are not effected by polarity so you do not need to worry about which side is positive and which is negative.
With your speaker installed your installation should look like the image above. Now you can install a WOW121 as seen in the image below.
You can now replace the shell on your tender, screw it back in place, connect the tender to the engine, and you are ready to run!
Important Soldering Tip
Please do not use any flux either liquid or paste on the mother board. Over time, the acidic properties of liquid or paste flux will begin eating away at the fiberglass PCB and will damage it. Use only Rosin-core solder or no-clean flux approved for electronics use.
TCS recommends the use of Kester "44" Sn63 Pb37, .015" diameter Rosin-core solder. Kester part number 24-6337-0007.
You can order this solder from the following retailers:
Digikey - PN:KE1110-ND
Techni-Tool - PN:488SO6775
Other solder tips
When stripping wire, only strip a tiny little bit of the insulation. Strip no more then a 1/64 of an inch. When the wire gets tinned with solder, the insulation will shrink back more. Try to not expose any more wire then half the length of the solder pad at most. In no case should solder or exposed wire wire ever be outside the boundary of the the solder pad you are attaching a wire to.
Click here for important information on properly Stripping and Tinning wire