This is a decoder install of a Digitrax DZ126IN decoder in an Atlas S2. The decoder has 6 pins and plugs into a socket on a light board on the S2. I thought this was going to be a piece of cake but it wasn't. Plugging the decoder in once I got to that point but getting the shell (cab part) off was not easy for me. Hopefully easier for you. The pictures should tell the story pretty well but if not get a hold of me. Also have the above along with other decoder installs here .... http://1fatgmc.com/RailRoad/Decoder-1/Decoders-Index.html Sumner
Outstanding article, and fortuitous timing! I have a couple of these locos coming (DCC ready). I've found 3 non-sound decoders that should be compatible with this loco (uses a 6-pin NEM651 interface): Digitrax DZ126IN (used in this article), TCS 1298, ESU 59827 (LokPilot 5 micro) Are there others I should consider? I'm leaning towards the LokPilot, mostly on the reputation of ESU decoders espoused here on TrainBoard (and the cost difference is not big enough to concern me). My only concern is that there is a capacitor that exceeds the envelope of the other 2 decoders by 0.5 mm (2.9mm vs 2.4mm) in height (decoder thickness). The installation photos above make it look like that should not be a problem. From photos of the decoder, the capacitor is on the pin-side of the decoder PCB, which faces the underside of the light board, but there seems to be significant room there. I use a Pi-SPROG3 and JMRI for programming and running DCC. Other than updating the decoder firmware, is there anything about this decoder for which I would need a LokProgrammer (or anything JMRI/SPROG cannot do with it)?
Sorry but I can't help you with the questions. I've stuck with Digitrax on most of my installs but a couple are TCS and a few are NCE if I remember right. I've got a lot to convert yet so cost is usually the overriding determination of what I'm installing. I basically just want the loco to run under DCC. I'm 77 and probably not a lot of years left in this so mainly up and running is my main priority. If I was younger or were operating with just a few locos I'd probably want the best and ESU from what others have indicated might be that. Maybe someone can help with your questions, Sumner
With a little more research, I've found that only the ESU 59827 and the Zimo MX616N are as small as, or smaller than, the Digtrax DZ126IN. The others are significantly longer, and it does not look like there is any more room for decoder length in the S2 (as shown in OP photos). Thanks again for the wonderful photos of your install, Sumner!
There is some room back in that section that the cab fits over. I could get the decoder back in there but not far enough for the pins to clear the socket face so had to get the light board loose to get the decoder pins in the socket. I considered cutting just a bit off the ends of the pin but decided against that. So depending on how wide the decoder is there still is some length to be used back in that area. Sumner
CT Electronik has the DZ776z that is I think even smaller (6.9 x 6.1 x 1.7 mm) http://www.tran.at/Produkte/DCX76z.shtml
Interesting. I can't find a U.S. supplier. A search does indicate that Streamline Backshop here might of carried them at one point. Anyone have any more info on this decoder and availability? Sumner
I was ready at some point to order online (I contacted them) and have it delivered directly in the US, or to some family members in France who should ship it to me in the US (or I would pick it up during a business trip) Haven't done it yet......
I'm sorry I failed to update this thread... I have ordered two Zimo MX616N decoders. The MX616N has an integral NEM651 connector on the decoder board itself, and is small enough to fit in the N scale Atlas S2. The Zimo decoders also have a reputation for excellent motor control. These two factors were paramount in my selection. While the CT Elektronik decoder circuit board is smaller, and is pre-wired to a NEM651 connector, the 50mm connector wiring harness would require too much room in the S2. It could probably be made to work, but would require additional means to mechanically secure it (and its wires) inside the S2. Thank you all for the suggestions.
I finally got around to installing the encoders in both ATSF S2's. Sorry I have no pictures, but the pictures posted by Sumner are far better than I could have provided. On the first one, I removed the cast metal long hood (for weight I presume), and then struggled with getting the cab off. I tried getting under the sides to clear the little catches, to no avail. I couldn't get underneath the second side with anything while holding the first side out clear of the catch. After taking a break from the frustration, I decided to see if I could get the light board far enough out to install the decoder, without removing the cab. I ended up getting it far enough out by sliding it forward (toward long hood end) enough to clear the roof of the cab, and then sliding if rearward above the cab to where the front of the board cleared the little pedestal at the front. This took every bit of slack out of the wires soldered between the chassis and the light board. I had to trim the pins on the decoder so they would fully seat in the socket, and the shorter pins were a little less flimsy to push into the socket. With the decoder installed, but not buttoned up, I tested it and it ran fine. I then maneuvered the light board back into place, replaced the tape holding the slack wires in place, and programmed the decoder with the road number for the address. I went ahead and read all the pages so I would have confirmed register data in my roster. There were a few settings that were different from the default values DP had shown. I ran it around my test loop on my dining room table a few times with the hood still off, just to make sure everything was OK. Then I tried to put the long hood back on. Uh oh. It wouldn't go. I tried reversing the motion I used to get it out (I had raised the front of the long hood (after removing the two screws from underneath, and then pulled firmly to get it out with a snap, but no damage). Putting it back together proved much more difficult. Upon closer inspection there is slight lip on the rear of the long hood that latches into the front of the cab. That was what snapped when I pulled it out, but there was no amount of pushing I could safely use to snap it back in place. I also realized the cab certainly was not going anywhere, and the rear of the long hood was held inside the cab by the two screws up through the chassis at the front of the long hood. So I took a small file and carefully filed off the tiny little rim around the rear of the long hood. The filed part is hidden once slid into the front of the cab. Be careful not to slip and mess up the paint job further forward on the long hood, since that would show after assembly. Masking tape is recommended for insurance while doing this filing. Also, be careful not to file the metal near anything electrical or mechanical, since those tiny filings are conductive too. With that rim filed flush, the rear of the long hood slid easily into the opening in the front of the cab, and I secured the front of the long hood by replacing the two screws underneath the chassis. I ran the loco again, and everything was perfect! For the second one, I didn't even try removing the cab, and after removing the long hood, proceeded to lift and slide the light board forward (toward the long hood end). This time I was more careful, since I had bent the horn on the front of the cab during the first install. I ended up sliding the light board forward to clear the front of the cab walls (not the roof or horn), and then rolling the light board over to one side of the motor, in between the railing and the motor, which gave me enough room to remove the shorting plug and install the decoder. I then rolled the light board back up on top, and secured it in place on the clips and pins on the top of the front pedestal. I secured the wires with tape as before. I then carefully filed off the lip on the rear of the long hood, slipped it into the front of the cab, and installed the screws holding the front of the long hood down on the chassis. I repeated the same steps of testing and programming the decoder before final reassembly, and everything was just fine, and with a lot less stress, knowing what to expect the 2nd time around. I haven't changed anything but the addresses yet, and the default settings on the decoder (BEMF is enabled) allow it to run reliably, if a little jumpy, at speed step 1, taking between 3 and 4 seconds per tie on the Unitrack! It is smooth as glass a few steps faster, and still takes over a second between ties. I could see the worms on the ends of the motor shaft were spinning slowly and smoothly, but the play in the truck gears was allowing the jumpiness at the lowest throttle setting. BTW, the Zimo MX616N encoder installs with the major IC facing away from the light board. Took me a while to confirm it, since they the Zimo documentation had no reference for pin numbers, only pin functions. I have seen a youtube video of installing a decoder in this loco, but it showed the cab popped off very easily, and the light shield underneath it too. Perhaps he had rehearsed the procedure enough to where the wedge and catch notch were worn down. But I would have been in a world of hurt if not for Summner's excellent annotated pictures and description.
