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Athearn PA-1   A & B Units
With Mars Light

This installation is a good first installation.

These directions probably can be used for most Athearn "Covered Wagons."

DECODER USED:  Digitrax DH83FX - 2 amp decoder with long addressing and Mars Light capability.

I wish they were all locomotives, diesel or steam, were this easy.  Diesels are notorious for not having any room to put in a decoder.  This covered wagon, with space to either side of the motor, makes it easy.  You will glue the decoder to the side of the motor with some Liquid Nails or Walther's Goo when you are all done.

Remove the headlight and the strip that runs to the front and back power pick ups that is on top of the motor.  You won't need either of these to finish the installation.

Athearn PA-1 A&B Units original "wiring."
Obviously, the B-Unit does not have a head light!

Pop the motor free.  It is held in place by a rubber mount.  Just rock it while pulling straight up on it.  Make sure you know it's mounting orientation.  Here's a little picture to help you.

Athearn PA-1 A&B Units - Top View of Motor Mount.

Break the little tabs off the bottom of the motor mount.  This is extremely important.  A DCC locomotive must have the motor isolated from the frame.  Now cut some pieces of electrical tape and cover the bottom of the frame under the motor so that there is no way the motor can ever electrically touch the frame.

Athearn PA-1 A&B Units After Installation.

I said this was the easiest installation yet, but I didn't say there wouldn't be a few small challenges.  Pop the strip off the top of the motor and solder the orange motor lead to it.  DO NOT try to solder the wire to strip while on the motor.  I almost ruined the motor frame.  It can't take any heat.  The strip is easy to pop off and put back on.  Underneath it is a spring.  If you are prepared, it won't get away.  It's not a very strong spring.  When done, snap it back on.

Attach the gray wire to the strip under the motor the same way.

Here's another small challenge:  Attaching the black wire.

Attaching the black wire on the A-Unit:

First, sand a spot on the front of the headlight mount until it shines.  Now solder the black wire to it.  You will need a gun type soldering iron of at least 100W.

If you have a resistance soldering station, here is an opportunity to show off.  Clamp the wire with a hemostat to the headlight mount.  Zap it with the resistance soldering iron and you're done in three seconds!  See the section on Soldering for more on using a resistance soldering station.

Attaching the black wire on the B-Unit:

Obviously, no headlight mount.  What to do, what to do!  On the side frame is a thin spot that is recessed a bit from the widest point on the frame.  I drilled a small hole through this thin spot.  Then I used a self-tapping #2 pan head (slightly rounded) screw.  Tin the wire and wrap it around the screw before you have it screwed all the way down.  When done, you will have no trouble putting the body back on.

I don't know what metal that frame is made from, but it is remarkably hard to drill through.  Be careful when you finally penetrate the frame that you don't penetrate the front truck as well!

Resume both assemblies here:

If you are doing the B-Unit, you are almost done!

In either case, sand the front power pick up tab until it shines.  Solder the red wire to it.  If you have a resistance soldering iron, here is your chance to show off again.

Now take another piece of red wire and solder the rear power pick up to the front power pick up.

If you are doing the B-Unit, you are done!  Glue the decoder to the side of the motor.  Use some rubber bands to hold it on.  Let it dry at least a day, preferably two.

Clip the ends of the other wires off so that they cannot ever short together.  I didn't want to cut them off, so I looped them up and stuck them into a piece of heat shrink tubing and glued it to the other side of the motor.

Installing the headlight and mars light:

Toss the light bulb that came with the locomotive.  It is easier to simply use a grain of wheat bulb than to fool with the stock headlight.

Connect one end of the grain of wheat bulb to the white wire.

Connect the other end of the grain of wheat bulb, plus an end from a second bulb, the mars light, to the blue wire.

Solder a 22 ohm, 1/4 watt or bigger resistor (R1), to the green wire.  Slide a piece of heat shrink tubing over it.  Attach the other end of the mars light to the loose end of the resistor, solder, and shrink the tubing.  For a little more on mars lights, see the section Using Minature Lamps.

Radio Shack
22 ohm, 5%, 1/2 W resistor

I'm good with wiring, but I'm open to better ways to mount these two lights.  Both will fit through the square hole in the original headlight mount.  I slid a piece of tubing over the mars light and pushed the bulb forward.  I then attached the mars light to the underside of the mars light.  I won't tell you how in hopes that you will come up with a good way.

The plastic headlight bezel easily pops out of the body.  With wire cutters, cut it into two pieces.  Trim the connecting plastic further to increase the gap and decrease the light coupling when reassembled.  Blacken the edges if you like.  They will both snap in and stay when you are done.  And by the way, you are done!

Mars light, forward, on with F1
Mars rate and keep alive brightness.  Try it at it's default value.  Then read manual and tweak to suit your preference.

The decoder installation was easy, but putting on the Kadee coupler is not any fun.  I'm going back to my steam locomotives.  Enjoy your new toy!


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