Athearn SD40-2 Decoder Installation featuring the RTR-MB1 Motherboard with Keep Alive®, WOW121-Diesel Decoder, and GEN-SH2 Speaker Kit by TCS.
First, remove the coupler box screws and the coupler boxes from both ends of the locomotive.
With the couplers removed the shell should lift right off the chassis.
Next, remove the wires from the original lighting board and remove it by lifting it from the rear of the engine.
Next, we will remove the rear weight by removing the two screws highlighted below.
Route the track and speaker wires through the two holes at the front of the enclosure, slide the 35mm x 16mm speaker into the housing, and glue the speaker and housing in place using hot glue or CA.
NOTE: You must be very careful to avoid getting glue on the speaker cone. Glue on the speaker will ultimately cause it to produce no sound and fail.
Next, clip the RTR-MB1 onto the motor just like the original lighting board and wire up the speaker, motor, and track according to the wiring diagram in your motherboard manual.
Though there are thru holes on the the tabs on the mother board for track power and motor power we do not recommend that you thread the wire though them. Please use the preferred method which is to tin the tab using rosin core solder only, tin the wire, then solder the wire to the tab by aligning it laying it straight down. Make sure the wire is short so that it does not go beyond the boundary of the solder pad. Please carefully note how neat and cleanly the wires are soldered to the tabs in this photo. There is no exposed wire off the edge of the the solder tabs. Never use flux for this solder work. Use only rosin core solder approved for electronics.
Solder in the lighting connections from the shell and install the WOW121-Decoder to complete the wiring of your installation. This mother board has a 1.5volt power supply to power all the original 1.5v bulbs that come with the Athearn locomotive. It can be configured for LED operation as well as the mother board has built in current limit resistors for LED use. Consult the wiring diagram for LED use.
All the original 1.5volt bulbs supplied with the Athearn loco were used. Both F0F and F0R have their own 1.5v+ supplies on each end of the motherboard so we simply soldered the forward and reverse light to the corresponding tabs. See your motherboard manual for complete wiring instructions.
Finally, you can replace the shell (it should slide over the installation easily), and replace the couplers on the engine.
Your WOWSound equipped engine is now ready to run!
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