| These notes do NOT apply
to installation with Digitrax's Athearn wire harness.
Athearn motors are
held to the chassis with a pair of rubber mounting pieces. They slip
onto the motor, then get pressed into four holes in the chassis. Remove
the motor and these rubber pieces - this requires you to disconnect
the drive shafts to the trucks. On the bottom of the motor, you will
find a small piece of metal bent down from the brush retaining clip.
This is there to make contact with the chassis when mounted. Either
bend this piece up to be flat with the rest of the clip, or snip it
off altogether. This will isolate that pole of the motor. It's not
a bad idea to place a piece of black electrical tape on the chassis
where this metal piece might make contact.
Solder the grey decoder
wire to somewhere on that same metal piece. If you do not have exceptional
soldering skills, you should remove the brush retainer to do this
soldering.
There are two ways
to connect the left rail to the black wire: the easy way (which is
adequate in most circumstances), and the best way.
The easy way: clean
the paint out of one of the motor mounting holes in the chassis. Strip
about 1/2" of insulation from the wire, and stick it in the hole
when pushing the rubber motor mounting pieces back in. This makes
a good connection to the chassis without soldering, drilling, or anything
else.
The best way: solder
a small flexible wire directly to the left side frame of each truck. Bring these two wires
together to solder to the black decoder wire. Be sure to string the
wire such that there is no interference with the truck's movement
when going around curves. This procedure eliminates many slip joints
that can hinder power transmission and/or create spikes in certain
situations. This is more important for people with large or complex
layouts than for people with small simple layouts.
When putting the motor
back in, do not re-install the top "power" clip - the one
that spans all the way from the front truck to the rear truck. Normally,
the connections at the trucks pickup power from the right rail, and
feed it directly to the motor connection. By removing it, you automatically
isolate that pole of the motor. Connect both truck tower connections
to the decoder's red wire. Doing this with flexible decoder wire,
such our D-Wire, will allow free movement of the trucks around curves.
Next, connect the
orange wire to the brush retaining clip on the top of the motor (like
the one on the bottom of the motor). Again, if your soldering skills
aren't great, it will be best to remove the brush retainer for soldering.
Lighting is particularly
problematic. It's mounted on a stanchion that is "riveted"
to the chassis. This is a very bad electrical connection. There are
two ways to solve the problem: the easy way, and the better way.
The easy way: remove
the bulb from the stanchion. Clip the back piece off, so there's nothing
sticking up where the end of the bulb used to make contact. Solder
the blue and white wire directly to the bulb, one to the side of the
base, the other to the small solder tip on the end. Be careful when
soldering to this - too much heat there can damage the bulb. This
is a 12-volt bulb, so you'll need a 100 ohm resistor in series with
one of the two wires. Attach the bulb to what's left of the stanchion
with two-sided foam tape - making sure no part of the bulb touches
the stanchion.
The best way: remove
the entire stanchion from the chassis. Find bulbs of the correct size
to mount in or at the headlight holes of the shell. Be sure to use
whatever resistor is needed for the bulbs you are using. Connect as
normal. Using this method, you might just as well add rear bulbs too
- something Athearn locos don't come with.
While you're
at it, you might just as well do what it takes to make that Athearn
run like a Kato. Learn more about it on our Athearn
Improvements page.
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