June 2004

Athearn's popular first N scale engine
seems a natural for a board type DCC
decoder but so far none is available.

There is plenty of room for a small
decoder without any modification
to the frame.  In this example I used
a Digitrax DZ121 but a DZ123, DZ143,
or any similar sized decoder would
also work.

The key to this installation is using the
existing circuit board.  The drawing of
the board at the right shows all the
steps taken to modify the board and
then make all the connections to
complete the installation.

Below are several photos to help clearly
see what the installation should look like.

In this photo you can see where a
section in the middle of the board
has been removed for the decoder.
I used a Dermal tool with a cut off
disk to do this.

After that the holes for the resistors
get drilled & the circuit traces between
the holes get cut.  Then reverse the
Led on the forward end of the board.

 

Next install a 270 ohm 1/4 watt resistor
at each pair of holes.  You will need
to scrape away the green plating from
around the holes before soldering.

Note in the close-up to the right how the
circuit trace has been cut between the
points where the resistor is soldered.
This was also done with a Dermal tool
and cut off disk.

I always recommend testing a new
decoder on a motorized test stand
before starting an installation.

After pre-testing the decoder, cut the
wires to the following lengths shown
in the photo.   Then strip & tin
1/16 inch on the ends.

Notice in the photo the red band on
the wires just as they come out of the
decoder.  Where space allows, I put
a band of heat shrink tubing on like
this to prevent any of the wires from
coming loose while the decoder is
being handled.

Remove the motor brush mounts from
the motor before soldering the orange
and gray wires to them.

Then solder the white and yellow wires
to the board at ends of the resistors
that are away from the LED's as shown
in the photo.

The blue wire gets soldered to the
large copper area shown at the
bottom of this photo.

Cut the plastic bar that goes across the
Top of the wire channel on each side.

Reinstall the motor brush mounts with
the orange wire going on the right side
and the gray wire going on the left
side.

Then solder the black wire to the tab on
the bottom of the left side and the red
wire to the tab on the right side.

Finish by tucking any excess wire length under the board and placing a piece of scotch tape
over the decoder to hold it in place.