Installation for a Athearn SD75M TCS WOW121-Diesel Decoder, GEN-MB1 Motherboard with Keep-Alive™
and UNIV-SH1-C Speaker 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-ATH-3 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-ATH-3 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

Athearn SD75M shown with the shell on prior to installation.


First, remove the coupler box screws as highlighted above in red and the coupler boxes from both ends of the locomotive.

With the couplers removed the shell should lift right off the chassis.

Remove the wires from the tabs on the original lighting board and set the shell aside. Next, remove the original lighting board.

Attach the GEN-MB1 and solder the track and motor connections to the GEN-MB1 according to the included wiring diagram.

Next, solder the lighting connections to the GEN-MB1. This locomotive uses 1.5v bulbs and the GEN-MB1 has a built-in 1.5v power supply so we don't need external resistors for this installation. Simply wire one side of each bulb to one of the pads labeled "1.5V", and solder the other connection to the corresponding solder pad on the GEN-MB1. As this locomotive includes ditch lights we soldered each one of those ditch lights to function pads 1 and 2 respectively.

Next, mount your speaker in the speaker enclosure and hot glue it facing out under the fan vents on top of the shell.

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.

Solder the speaker wires to the motherboard according to the included wiring diagram.

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

Finally, plug your WOW121-Diesel decoder into the GEN-MB1 motherboard and your installation is complete.
Replace the shell (it should slide over the installation easily), and replace the couplers on the shell.

Your WOWSound equipped Athearn SD75M is now 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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