This installation is for a HO Scale MTH 4-8-2 L-3C Steam using a TCS WOW121 Steam Decoder, AS-MB2 NC Motherboard, KA3 Keep Alive®.

This was performed by our friends from DCC Xpress installations.
They offer high quality WOWSound installations for a flat rate complete with free return shipping!
You can find them at:

Kit Coming Soon! We are in the process of assembling all the items shown here into a new WOWKit.
Please check back here to see the new WOWKit when it arrives.

Important Soldering Tip:
Please do not use any flux either liquid or paste on the mother board. It will damage it. Use only Rosin core solder approved for electronics use.
We recommend to use only Kester "44" rosin core, SN63PB37, .015" diameter, part number 24-6337-0007.
This can be ordered from Techni-Tool under Techni-Tool part number 488SO157


MTH 4-8-2 L-3C Steam shown with the shell on.

To start this install, first remove the two screws shown highlighted above in red.

Next, remove the five additional screws highlighted above.
Be very careful to collect in order the various screws, springs and washers, in order to be able to reassemble them correctly.

Lastly, the single front screw needs to be removed. With this done, very carefully lift off the locomotive shell from the chassis.

With the shell removed, clip the wire leads from inside the shell and remove the plastic shroud and lighting board highlighted above in red.
Also remove the small track pickup distribution board on the chassis as shown.

Collect the track pickup wire leads and splice them progressively into two new remaining leads as shown.

Re enforce or solder new motor leads to the motor and using small lengths of TCS 3/32" and 3/64" shrink tubing, insulate these connections.

Clip the remaining leads from the rear lighting board as shown above.

Out of the remaining wires found in the shell, select the rear cab LED wire lead and front headlight wire lead and splice in new wire leads as shown above.
There are many wires inside this shell and a additional board further up inside the shell. Though careful testing, these particular leads were isolated and identified.

Paying attention to the wire lead order and selection, splice these wires into the mini 6 pin and mini 2 pin female connector plug. The two pin in typically used
for track pick up and for this installation, the 6 pin was used for the 5 remaining wires for the motor and lighting wire connections.
With the locomotive properly wired, reassemble she shell onto the chassis in reverse order, being sure to route the wires carefully to avoid
potential shorts.



With the locomotive complete, remove the four screws located at the corners of the tender shell and lift the shell from the chassis.


The tender shown with the shell removed.


Remove the four screws highlighted above in red and then release the four tabs shown to release the original lighting board.

With the rear LED board removed, unsolder all but the green and purple leads. This board will be reattached to the frame with these two leads attached.

Pre wire in corresponding male 6 and 2 pin connectors for the wire leads that will feed into the tender from the locomotive plug.

Using double sided foam tape, mount the AS-MB2 NC to the center of the frame as shown. Using a small strip of the same tape, secure the KA3 Keep Alive®
to the frame. Solder the track, motor and KA3 to the motherboard according to the included wiring diagram.

Rewire the speaker wire leads in series as shown above and solder these leads to the motherboard.

Solder the lighting leads to the AS-MB2 NC according to the included wiring diagram. Using the saved screws. reattach the original light board on
top of the KA3. This will place the LED in the original, correct position.

Reattach the speaker enclosure. You can now plug in the Wow 121 Steam decoder.

Lastly, in order to keep the wires neat and prevent possible shorts, lace the wires into a bundle using lacing cord, which is a wax impregnated string 
used for wire bundling and making harnesses. There are many choices of lacing cord available from Digikey
We use part number 802534B BK032-ND

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

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