This installation is for a HO Scale Bachmann GP38-2 using a TCS WOW121-Diesel Decoder, AK-MB1 Motherboard with built in Keep Alive™
and UNIV-SH1-C WOWSpeaker kit by.

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-3 which was used for this installation.
AK-MB1 Motherboard with Keep Alive™ WOW121-Diesel Decoder UNIV-SH1-C Speaker Kit
Click here for more information on the WDK-ATL-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

HO-Scale Bachmann GP38-2 shown prior to installation.


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

With the couplers removed, reach underneath and carefully pull the tank cover off. Remove the two screws highlighted above in red and then
while gently pulling outwards at each end and along each side of the frame, lift the shell off of the frame.
Take care to release the handrails as you lift off the shell so they don't break.

The Bachmann GP38-2 shown with the shell off. Remove the two screws highlighted in red above, then remove the wires from the original lighting board
and remove it from the chassis.

With the original lighting board removed, trim, tin or lengthen the wires as necessary. You will notice three caps highlighted above in red inside the
frame on top of the motor. Using snips, remove these three parts. They are not needed and will prevent the locomotive from running smoothly with
the new decoder installation.

Next, lift off the front LED mount and trim it along the line highlighted above in red. This will allow space for the future speaker installation.

With the front LED mount trimmed, secure this LED back into place and using a small amount of hot melt glue, mount this assembly back on to
the frame as shown above. We used Kapton tape here to fasten the wire leads and to prevent interference with the speaker.

Attach the AK-MB1 to the motor mount and secure this assembly to the frame using double sided foam tape. With the LED in place, solder the track,
motor, front and rear LED leads to the AK-MB1 according to the included wiring diagram.

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, mount this assembly into the
top of the shell as shown above. It is critical to orient it as shown so it will be mounted between the front LED and the AK-MB1 and there will
be no conflicts with the other components when the shell is reattached.

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.

We found that by drilling two 1/8" holes into the tank cover directly underneath the holes found below the motor, the sound from the downward facing
speaker will exit the frame more efficiently and the sound quality and volume is greatly improved.

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 tank and coupler assemblies. Be sure to be mindful of wire routing and reassembly of the shell as to not damage  or foul the installation. Your Bachmann GP38-2 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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