This installation documentation is for the Walthers F7A. This installation uses the WDK-ATL-7 kit which includes the WOW121-Diesel decoder, AS-MB2-NC, and UNIV-SH4 speaker kit. This istallation was performed by A.G.
To start off this install, we must first remove the front coupler screw and it's housing. With this coupler 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 EMD F7A shown with the shell off. Remove the wires from the original lighting and then remove the four screws located as highlighted above in red on the two boards and remove them from the chassis.
Shown with the lighting board removed. Trim, tin or lengthen the wire leads as needed.
Take note of the lighting leads for the purpose of easing the reinstallation.
With the boards removed, remove the single screw highlighted above in red and remove this entire piece from the installation. It will not be needed.
Mount the AS-MB2 NC to the frame as shown above using double sided foam tape. Solder the motor and track pick up leads to it according to the included wiring diagram. Using small lengths of TCS 3/32" and 3/64" shrink tubing, insulate these solder leads if needed. We chose to pre-route all the wire leads for a neat and trouble free installation.
Using the same tape, with the 25mm x 14mm WOWSound speaker inserted into the UNIV-SH4 housing, securely mount this assembly to the frame as shown. Solder these wire leads to the mother 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.
With the speaker in place, solder the lighting leads to the motherboard according to the included wiring diagram. Fot this installation, the front headlight is soldered to FOF, the running lights to pad #1 and the Flashing Mars light to pad #2.
TCS motherboards include on board current limit resistors for LED use. There is no need to apply external resistors for LED use.
Likewise, with the same double sided foam tape, mount the KA3 Keep Alive® to the frame along side the AS-MB2 NC and solder these leads to the motherboard as shown.
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 www.digikey.com. We use part number 802534B BK032-ND
Now you can close up the locomotive and reinstall the coupler assembly. Be sure to be mindful of wire routing and reassembly of the shell as to not damage
or foul the installation. Your Walthers Proto EMD F7A is now WOWSound equipped and ready to roll!
Important Soldering Tip
Please do not use any flux either liquid or paste on the mother board. Over time, the acidic properties of liquid or paste flux will begin eating away at the fiberglass PCB and will damage it. Use only Rosin-core solder or no-clean flux approved for electronics use.
TCS recommends the use of Kester "44" Sn63 Pb37, .015" diameter Rosin-core solder. Kester part number 24-6337-0007.
You can order this solder from the following retailers:
Digikey - PN:KE1110-ND
Techni-Tool - PN:488SO6775
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