Athearn GP40X Decoder Installation featuring the RTR-MB1 Motherboard with Keep-Alive™, WOW121-Diesel Decoder, and Speaker Kit by TCS
First, remove the coupler box screws and the coupler boxes from both ends of the locomotive.
Next, remove the two screws on either side of the last wheel set in the rear truck.
With the couplers and frame screws removed the shell should lift right off the chassis.
Remove the wires from the original lighting board tabs.
Next, remove the original lighting board by lifting it from the rear of the engine.
Remove the rear weight from the engine by removing the 3x screws highlighted below.
Mount the RTR-MB1 on motor just like the original lighting board.
Solder the two violet wires to your 35mm x 16mm WOWSpeaker, mount the speaker into the speaker housing and glue mount it on the rear frame posts.
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.
With the speaker installed you can begin attaching the speaker, motor, and track wires to the RTR-MB1 in accordance with the wiring diagram in the 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, 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. The white wire solder pad is the forward 1.5v solder pad for the front lights. The yellow wire solder pad is the reverse 1.5v solder pad for the reverse lights. The lower headlight bulbs are connected to the solder pads marked "1". The solder pad marked "1.5V" is the common power source for the bulbs.
In order to keep the wiring neat and to prevent pinched wires and possible shorts, using wax lacing cord, bundle the wires into a harness.
Finally, you can replace the shell (it should slide over the installation easily), screw the shell in with the screws beneath the trucks,
replace the fuel tank, and replace the couplers on the engine.
Your WOWSound equipped engine is now ready to run!