Athearn SD40-2 Decoder Installation featuring the RTR-MB1 Motherboard with Keep-Alive™, WOW121-Diesel Decoder by TCS

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
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-1 which was used for this installation.
GEN-MB1 Motherboard with Keep Alive™ WOW121-Diesel Decoder 28mm Speaker Kit
Click here for more information on the WDK-ATH-1 and the rest of the WOWDiesel Kits line.

The Athearn SD40-2 prior to installation

To begin, first, remove the coupler box screws and the coupler boxes from both ends of the locomotive.
Gently grasp the shell on both sides, pulling outward while lifting and remove the shell.


The Aethearn SD40-2 with the shell removed. In this installation as all the original connections are direct to the frame,
it needs to be converted into wiring to be able to install the RTR-MB1 motherboard.

Using needlenose pliers, carefully open the tabs securing the front light shown above, releasing it for removal.

The Aethearn SD40-2 with the front light removed.

Next, unclip the elecrical connection and using a blunt end probe or file, push on the tabs underneath the frame to release the motor from its mounts.

The Aethearn SD40-2 with the motor removed.

Pull outward as shown in red on the metal clip and remove.

After bending the small tabs in the opposite direction on the clip, solder a motor wire to the underside as shown.

To ensure proper insulation, cover this solder with Kapton tape.

Shown with the mounts reinstalled.

Isolating the frame.

Next, add a solder connection on the top connection of the truck.

Solder the motor and track connections to the motherboard as shown.

Next, with the 25 x 14mm speaker wired and inserted into the UNIV-SH4-C enclosure and mount this assembly into the top of the shell.
Solder this and the lighting wires onto the motherboard as per you installation diagram.

In this installation we added a 1/41K ohm resistor to each lighting lead.
To ensure a neat and clean installation, prevent pinched wires and avoid potential shorts during reassembly and operation, lace the wires in to a bundle.
Reattach the shell and couplers and yYour WOWSound equipped engine is now 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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