This installation is for a HO-Scale Kato SD40-2 using a TCS WOW121-Diesel Decoder, AK-MB1 motherboard with Keep Alive™
and UNIV-SH4C WOWSpeaker kit by TCS.

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-ATL-2 which was used for this installation.
AK-MB1 Motherboard with Keep Alive™ WOW121-Diesel Decoder UNIV-SH4-C Speaker Kit
Click here for more information on the WDK-ATL-2 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-Scale Kato SD40-2 prior to installation.


To start off this install, we must first remove the front and rear couplers as highlighted above in red and their housings.
Once that is complete, the shell will lift off of the chassis. Do this by holding the fuel tank with one hand and lifting the shell off by
pressing up underneath the end platforms with your other hand.

With the shell off, we can now remove the original light board. Remove the wires from the board and the board can easily be unscrewed from the motor mount.
Make sure to save the two screws as they will be used to secure the AK-MB1 back in place.

In this particular locomotive there was a lot of exposed motor tab and wire so we reworked and shrunk wrapped the motor connections prior
to installing the AK-MB1 on top of the motor.

With the motor connections corrected we can mount the AK-MB1 in place of the original lighting board, screw it down, and solder the motor and
track connections to the board.

This engine typically uses LED's mounted directly to the original lighting board or decoder as seen in the second picture of this installation process.
For our installation we decided to use 2 of the TCS 1417 (2x wired surface mount sunny white LED kit) as a replacement for the existing LED's.

To mount these LED's I placed a small dab of hot glue on the end of the light tube and pressed the LED facing into the light tube into the hot glue.

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.

With all 4 LED's mounted on the light tubes you can connect the LED's to the AK-MB1 motherboard.

With the lighting soldered in, insert the 25mm x 14mm speaker into the UNIV-SH4-C enclosure and using double sided foam tape, mount this assembly to the frame
behind the AK-MB1.

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.

Next, clip the speaker wires to length and solder them to the speaker connections on the AK-MB1.

Finally, install the WOW121-Diesel decoder onto the AK-MB1 motherboard.

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

Replace the shell (taking care not to pinch any of the wires), remount both of the couplers, and your SD40-2 is now WOWSound equipped and ready to run!

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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