A couple years ago I purchased an Atlas RS-1 on ebay. It’s an old fashioned DC loco and nothing DCC friendly about it. I got the most basic Digitrax decoder because I saw no chance of fitting both a decoder and speaker in the narrow shell for sound. I had to splice into the power wires and solder the 4 basic decoder wires. After completing that, I had a heck of a time fitting everything back into the shell and clamp it back into place. Several times I broke one of the soldering joints and had to resolder it. Finally I squeezed everything in and was able to clamp the shell down so it clicked into place.
I assigned the decoder address and started a test run. It ran fine forward but when I reversed it, it derailed at the first turnout it passed over. I could easily see why. By stuffing the decoder and wiring back into the one small space inside the shell that would accomodate them, the assembly was pushing down on the front of one of the power trucks causing the rear wheels to raise up off the track. I took the shell back off and tried to rework everything and discovered I could no longer power the motor. The light was coming on so it was getting power but the motor was not moving. I suspect what might have happened is that in stuffing everything into that small space, the tape I was using to insulate the soldered joints might have come off and caused a short which damaged the decoder.
I really like this engine and want to make it part of my roster. I’m hoping there is a smaller sized decoder that would more readily fit in the narrow shell. Just a basic decoder to control the motor and work the headlight is all I need. Can anyone recommend a good HO decoder that would work in this loco.
I am not a decoder expert but I hardwired a TCS MC2 decoder in a Bachmann GE 44 Tonner recently and it is quite a small decoder with good slow speed control.
I don’t know for sure if it will fit in your RS1 but you can go on TCS web site and compare MC2 dimensions with your decoder.
If this is HO, the Kato-made ones, it IS DCC ready. You just repalce the palstic ‘board’ with an Atlas /Kato board format decoder such as the TCS A4x. Plugs and sockets do not “dcc ready” make - the P2K S1 has an 8 pin socket yet is NOT DCC ready (despite the claim on the box!) since the motor is not properly isolate. Motor isolation is what makes DCC Ready.
The only complicated part about the Atlas/Kato Alcos is mechanical - cutting down the light bars so you can put in two lights or LEDs and have independent lights front and rear instead of one bulb in the middle.
Randy touched on what your problem is … the two light bars. They just don’t allow any room for anything else to fit into the shell. The simplest fix is to cut the light bars shorter - about a quarter inch inside of the ends, then shrink-tube an LED onto the end of the remaining stub.
The TCS A4X decoder is a drop-in replacement for the old plastic board, the the decoder doesn’t require extra resistors to be added for the LEDs - they can be attached directly to the decoder as it already has resistors on it for the LEDs.
There is no old plastic board to replace. I don’t know how old this loco is but it is wired the way my Atlas locos from the 1980s were. Wires run directly from the powered trucks to the motor. I had to splice a basic decoder into those wires and solder them. It definitely can’t use a drop in decoder the way more modern DC locos do.
I was able to get a Digitrax DH123D into my Atlas RS-1. The decoder is taped to the top of the motor, I think and I believe I used the light tunnels, as the body comes off without wires. I need to take it apart to remember how I did it, maybe I will do that today.
Interesting, I am only aware of maybe 3 versiosn of the RS-1, the original Kato one with the plastic board, the first Atlas motor ones with a regular circuit board, and the later Atlas ones that add an 8 pin socket. At least in HO. Was there an even earlier one, from when Roco made Atlas locos, which would just have wires?
Yes, I have a large stash of that era RS-3, since I need lots of them. I’ve converted a bunch. So far motor only, but the next couple I am going to put sound in.
That is exactly what it looked like. I tried to cram the Digitrax decoder behind the motor (to the right of it in this picture). I managed to squeeze it in and still get the shell back on but it was pushing down on the powered truck to the point where it forced the wheels closest to the motor raised up.
Maybe I should have tried it on top of the motor as NP2626 suggested. I’m going to see if that works if I haven’t fried the decoder.
Does anyone know a method of testing to see if a decoder is still good other than to wire it to the loco and see if it still works. I tried clamping the lead wires to my programming track and seeing if I could set the address that way. It didn’t accept it which is why I think I might have fried it.
If you want sound, Loksound makes the same style board as well (Loksound Select Direct) and there’s plenty of room to install a small speaker in the end over the truck at either (or both) end as the RS1 doesn’t have the separate weights over the trucks like the RS3 does.
I have an article saved that shows how to do it in an RS3. Not really that difficult - kind of easy if you just completely give up one of the weights, or you can slice it down. That fits a bigger speaker than you could cram in the cab, plus you don;t see it.
As for the OP - those two long brass fingers on either side are clipped under tabs on that plastic. The pop off. Then the whole big piece of grey plastic comes off, leaving a space for either the various board decoders (add a third - the Digitrax DH165A0 (or the DH165K0 - for extra cost you can have them solder on littpe pieces of wire for the connectors on the truck wires to slide on to). So that’s 3 options for motor decoders, or the Loksound Select Direct is a drop in board sound decoder. Or, with all that room, you can now hard wire a regular harnessed decoder, no need to cram anything. That grey plastic ‘board’ eats up a lot of space.
I misunderstood what you meant by a plastic board. I thought you were referring to a circuit board. Many of the more recent DC locos I have converted had a small circuit board which could be swapped out with a decoder in its place.
I like that the decoder has terminals to be soldered to. The Digitrax decoder I tried to use had nothing but lose wires that need to be spliced into and soldered to the existing wiring.
