This installation is for a HO-Scale Kato EMD SD90-43MAC using a TCS WOW121-Diesel Decoder, AK-MB1 Motherboard with built in Keep Alive®
and UNIV-SH1-C WOWSpeaker kit.

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:

These items are available in the WDK-KAT-1 which was used for this installation.
GEN-MB1 Motherboard with Keep Alive™ WOW121-Diesel Decoder UNIV-SH1-C Speaker Kit
Click here for more information on the WDK-KAT-1 and the rest of the WOWDiesel Kits line.

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

HO Kato EMD SD90-43MAC shown prior to installation.


    To start off this install, we must first remove the front and rear coupler screws highlighted in red above and their housings.

With the couplers removed, while gently squeezing along each side of the shell, gently lift the inner shell off of the frame.
Take care to release the handrails as you lift off the shell so they don't break.

The Kato EMD SD90-43MAC shown with the shell off.

Remove the wires and the two screws highlighted above in red and remove the lighting board from the chassis. Save these screws for reinstallation.

With the original lighting board removed, trim, tin or lengthen the wires as necessary.


To make a new motor connection, first trim off the metal motor pickup tabs as shown above left. Create a connection point to each of these, solder the new leads,
then insulate these with shrink tube insulation. We used small lengths of TCS 3/32" and 3/64" shrink tubing.

Attach the AK-MB1 to the frame with the saved screws and solder the motor and track pickup wires according to the included wiring diagram.

Next, carefully remove the two existing LED's from each end of the original lighting board.


Take the original front LED and using a small pair of pliers, bend the ends as shown to fit onto the front of the AK-MB1. This will become the front ditch lights.
Solder it in place to pad #1 as shown above, facing into the end of the light tube. Install the rear LED in a similar manner as shown.


In this installation, we decided to add a new LED for the headlght to allow separate functional operation of the ditch lights. To do so, clip the length of the original
front LED headlight tube as shown above left and then using a small dab of hot melt glue, place the new LED onto it, insulating the leads with
shrink tubing as shown above right. We used TCS part #1288 Sunny White 3mm LED for this. Solder these leads to the AK-MB1 according to the included wiring diagram.

We have found that LED light output is brightest when shinning directly into the end of the light tube, but in some circumstances they may be placed along the length
of the tube as well with satisfactory results. In doing so, white light LED output would be least affected, while non white LED output will be more affected by placement.

TCS motherboards include on board current limit resistors for LED use. There is no need to apply external resistors for LED use. 

With the 35mm X 16mm WOWSound speaker inserted into the UNIV-SH1-C enclosure, using double sided foam tape, securely mount this assembly into the front top of the shell
as shown above. Solder the speaker wire leads to the AK-MB1 according to the included wiring diagram.

If your speaker enclosure installation covers the portholes on the enclosure, we recommend adding new port hole(s) similar to the original porting. Be sure that the new portholes are the same size and amount of the original and are vented freely into the locomotive We have found introducing a port of the correct size greatly increases the volume and sound quality of the installation. Too much or too little porting decreases the sound quality.

Shown with all the components installed correctly. In order to separate the front headlight output visually from the ditch lights and prevent light spillover,
we placed a small piece of black electrical tape into the front roof of the shell to isolate this light.

You can now plug in your WOW121 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

Now you can close up the locomotive and reinstall the coupler assemblies. Be sure to be mindful of wire routing and reassembly of the shell as to not damage 
or foul the installation. Your Kato EMD SD90-43MAC is now WOWSound equipped and ready to roll!

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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