Here I will document the step I take that I think are a bare minimum when it comes to installing DCC into a pre-RTR locomotive.
First is our victim. Its a run of the mill Blue Box SD40-2 that has seen a medium amount of running. It was given to me by a cusomter for a sound install with a Soundtraxx Tsunami AT-1000 and a Tony’s Trains’ mini speaker and enclosure. Not my choices in particular for this loco, but this is what he wanted to install. You will notice the virginal look of this typical loco. Everything that is done here can be done to ANY Athearn Blue Blox.
Step 1. Dissasemble the drive.
The motor and trucks are removed by removing the clips holding them in. Be careful of unseating the motor and make sure the white rubber motor mounts are in prime condition. A replacement from Athearn is available with plastic mounts and screws.
Step 2. Clean and relube the trucks. The trucks are dissasembled and put into a bath of warm soapy water. A good scrub is used to remove the factory oils from the gears. Wheel sets are taken apart and scrubbed like anything else.
Bits dryed on a nice fluffy towel. Dab the parts as to not stress them.
The wheels sets are reassembled and regauged. Do NOT apply any sort of lubricant to the bearings as it will only collect dirt and impede electrical flow.
Labelle grease is applied to the gears and gear pegs. Trucks have a wire soldered to the side frame m
David, LOL on mini speaker. I can’t believe that TTX recommended that speaker. I use the larger medium. Maybe you should let him hear what it COULD sound like??
Athearn BB motors suffer 2 flaws. First is the springs utilized are too large and need to be halved (halving the spring forces the motor to draw less amps). Second is that it gets the left rail power through the frame. We need to correct both of these flaws before a decoder can be installed.
Remove lower clip.
Dont forget to watch out for that flying spring. Remove the spring and cut in in half. Solder to the “taller” side of the clip and apply a wire.
Notice the spring in the bottom picture. It was cut by half.
The bottom clip also has 2 prongs that need to be clipped off. Clip them off and file them flat. Reassemble the bottom clip to the motor. Apply 2 layers of Kapton tape and trim. Reinstall the white motor mounts.
Repeat the steps for the TOP clip and reinstall the motor to the frame.
Athearn BB locos are the Anit-DCC as even the top of the motor precludes you from attaching a board directly to it. We need to make a shelf. I use .125 styrene and cut a hole in the middle of it to clear the motor’s top clip. I then drill holes for the truck leads and motor leads.
The decoder board is then secured to the plastic shelf with more Kapton tape. Wires are threaded through and connected to the decoder. Test for proper decoder behaviour at this point as well as correct direction orientation. If the loco runs contrary to throttle direction, now is the time to swap the motor leads on the decoder.
A smaller shelf is constructed and is put into place for the speaker. Make sure the shelving does not interfere with flywheels or universals or gear tower. The supplied speaker is then mounted on the smaller shelf.
It is planned out so there is just enough room for the cap. notice the nice fit ahead of the speaker.
Light leads are made from 3mm Warm White Leds, 1000k resistors, 1.5mm Fiberoptics, wire and heat shrink tubing. These are inserted from the inside of the shell and give good lighting.
Thats it. You are done. All thats left is to put the shell back on and program.
Hope this helps. The next evoltuion would be to replace the motor with something of more quality as well as the wheel sets with something plated.
I’m sure many people will find your tutorial useful, especially with the detailed photos. One thing I always do differently, though, is exchange the top and bottom motor brush clips so the smooth clip is on the bottom of the motor.
Swapping clips top to bottom is a good idea - avoids any potential problem. Also caustion for someone doing this for the first time (or rather, taking apart a Blue Box loco for the first time) - if you remove the top and bottom clips at the same time, the motor WILL fall apart, those clips are all that holds it together. So hold the ends on when you pop the second clip, then put one back on while you solder the wire to the removed one, reattach the clip with the wire not soldered on before removing the other clip.
Also note the neatness of the wiring - wires hanging out all over the place are BAD - they WILL get caught in the drive at some point if they are not cut and contained. Back in the early days, stick tack type material was often used to hold wires. Also not a great idea, the stuff flows when warmed up. Kapton tape is not cheap, but a small amount goes a long way, and it doesn’t leave a sticky mess like regular vinyl electrical tape. 5 or 6 years ago I broke down and just picked up a roll of Kapton tape from a train show vendor. Can hardly tell how much I’ve used. This roll should last practically forever at this rate.
I think you misread Randy’s comment. He says “…note the neatness of the wiring…” I think he was saying that your wiring is very neat, not the opposite.
The subject was a F7B that serves as the pusher for my rotary snowplow.
On my conversion I didn’t install sound, so I didn’t need to build the speaker platform. I used a simple two-function decoder.
With the Blue Box analog (DC) locos the wheels on the right side of the trucks energize the inverted “L” brackets that—through the flat metal conduit running the length of the top of the motor assembly between the trucks—contacting the top of the motor through the clip that holds the spring and magnet- - I will refer to as the motor brush.
The left set of wheels directly contact the frame, energizing the frame, which in turn contact the bottom of the motor through the motor brush which has two contacts or “prongs”- -for lack of a better term, to the frame. The frame also provides power to one side of the light assembly.
The opposite side of light bracket is connected, via a spring clip, through the flat metal conduit along the top, to complete the circuit and energize the bulb.
With me so far- -good!
What I did was swap the bottom brush clip; with the contacts to the frame, with the top brush clip; without the contacts, electrically isolating the motor. As an added measure of security I cemented a piece of 0.010” piece of styrene onto the frame; between the frame and the bottom of the motor. This was fitted between the stock motor mounts.
Here’s where it get’s interesting…
I wanted to keep the lighting function of the original headlight to provide a prototypical work light inside the F7B body.
To electrically isolate the bulb assembly I clipped the bracket where the step-down is. I cemented the two halves of the light bracket together with a piece of 0.040” styrene between them to maintain the position of the bulb in the body.
I have three of the first-run Amtrak P-42s and Loksound Select decoders just waiting for me to jump into the project. Your clear instructions are all I need to get this project to the front burner!
I must add that I cannot rely on the frame for an electrical path. These installs are for customers, not for yours truely…I don’t want to see them back any time soon and I am unable to shortcut. Using the light clip for half of the signal means that you are relying on the bolster for electrical continuity. A marginal idea at best as it tends to get dirty. It’s ok for DC but dcc is a bugger for a clean signal. I always bypass this weakness with wires soldered directly to the side frame rivets. David B
Direct wiring - definitely the best. It seemed that back in the pre-DCC days, the Blue Box locos had more reliable contact via the bolsters and frame. I always repalced the bif top clip with a wire to the front and rear truck, but the frame side we never seemed to have to modify. On the descendent RTR models, I’ve had 50% failure without bypassing the bolster/frame connection with direct wires.
That front light clip on BB models is NEVER tight, that rivet is always loose and while a convenient point to slide on a connector, it’s far from ideal. If NOT running wires from both sides of the truck, the next best thing would be a brass screw in the frame, with the decoder wire soldered to it. But all wires is best of all.
The inboard speaker shelf is glued to the underside of the decoder shelf via a .125 shim. Because I’m using thick styrene, solvent makes this a very strong joint. It clears the flywheel by .060 thou. The legs are tacked down with ca.
