This installation is for a HO-Scale Athearn MP15-AC using a TCS WOW121-Diesel Decoder, IB-MB1 NC Motherboard with built in Keep Alive™
VR 1.5 Voltage regulator and UNIV-SH4-C WOWSound 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-11 which was used for this installation.
IB-MB1-NC Motherboard with Keep Alive™ WOW121-Diesel Decoder UNIV-SH4-C Speaker Kit

Voltage Regulator

Click here for more information on the WDK-ATH-11 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 Athearn MP15-AC 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 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 Athearn MP15-AC shown with the shell off. Unplug and remove the wires from the original lighting board, remove the two speaker mounting
screws highlighted above in red and remove the speaker. We will not be reusing this assembly as we found by placing a newly enclosed higher quality WOWSound
speaker facing downwards, the sound volume and quality was greatly increased, allowing it to escape out of the shell realistically through the front vents
and front truck assembly. This arrangement also helped reduce unwanted audio vibrations in the shell.

Remove the two screws highlighted above in red and lift the board from the chassis.

Next, clip off the cap found on the top of the motor and discard it. As the IB-MB1 NC has built in capacitors, this additional piece will interfere
with the smooth running of the locomotive.

The next step is to address the lighting. As the IB-MB1 NC does not have connections for the original 1.5 volt bulbs which are wired in series with a resistor, there are steps that must be taken to utilize these bulbs including adding in a TCS VR1.5 Voltage regulator to supply a proper power supply. We will also be changing the bulbs leads form a series to a parallel arrangement. To replace them all with LED's would not be feasible and you would lose look of the bulb lens face poking through the shell.
To begin, clip the front and rear light connector from the shell lighting wiring as highlighted above in red.


Remove the rear cab, then remove the three screws holding the original front and rear light boards and remove them from the shell.
The front board's screws will not be reused as we found with the speaker in the front and with the board secured only on one end, the board
vibrated and caused distortion to the sound. Instead, we will be securing across it's entire surface to eliminate this possibility.

Once removed, combine the two original leads on the front board (shown as black into white) into one convenient wire lead and then add a
common (shown as blue) lead to the solder point as shown above. This wires them in parallel.

Now, as there is a 180 ohm resistor on each light board, it will be necessary to bypass these for the lights to function properly.
To do so, first add a small dab of solder to each end of the resistor area as highlighted in red above.

Then taking a small length length of tinned wire, solder this wire as a 'bridge' onto the dabs of solder.

Trim off the ends of the wire. Here the resistor is shown with a properly placed bridge now across the resistor.

Likewise do this on the rear board, combining the two original leads into a single wire (shown as black into yellow) and then adding a common lead
(shown as blue) to the solder point as shown above. This wires them in parallel.

This resistor on the rear board also will need a bridge like the front board.


Using double sided foam tape, mount the front board into the front top of the shell to secure it and eliminate vibration. With this done,
after inserting the 25mm X 14mm speaker into the UNIV-SH4-C housing, mount this assembly also with double sided foam tape on top
of the lighting board.

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.


Again, as we are utilizing the original 1.5 V bulbs, before mounting the IB-MB1 NC it is necessary to also bypass or 'bridge' the two LED current limit resistors
on the bottom of the motherboard, highlighted in blue above as 'before' and 'after'.

In order to fit the IB-MB1 NC flush onto the frame, trim off the two frame mounting tabs as shown above in red and remove the speaker housing.

Using double sided foam tape, mount the IB-MB1 NC to the frame and solder the track and motor leads to it according to the included wiring diagram.


Solder the speaker leads to the IB-MB1 NC according to the included wiring diagram. At this point, we will add the TCS VR 1.5 Voltage Regulator.
This component has three wire leads. The first wire, the black and white striped wire, will be soldered to the negative cathode lead on the capacitor
highlighted in blue above.

The VR 1.5 tan wire will become the common lighting lead and the blue will be the 12 volt lead as shown wired above.
The front and rear lighting leads previously combined will be soldered to the IB-MB1 NC according to the included wiring diagram.

The Athearn MP15-AC shown wired and ready for reassembly. To ease this, remove the top access panel and feed the VR 1.5 through it.
The 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

Place the VR 1.5 carefully into the shell and replace the access panel cover. 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 Athearn MP15-AC 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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