I decided to replace the decoder in my GP38 which had a dual mode decoder. Ordered and installed a TCS AMD4 decoder which didn't seem to respond at all. I noticed that it wasn't a tight fit to the frame. I reinstalled the dual mode decoder just to make sure it wasn't the engine and the engine ran normally. So, took it out and reinstalled the TCS AMD4 and still no response and couldn't get any tighter fit and decided this must be the problem. At this point I decided just to put the dual mode back in the engine for the time being and now that won't respond at all. Don't know what to think at this time. Help anyone? Papa
check where the decoder contacts the frame. sometimes it's required to add a little more solder to those pads to they connect better. No lights, no nothing? don't forget, TCS has a no questions exchange policy. Even if it is the decoder, they'll ship you a new one.
I understand they have a very good exchange policy , but I have no reason to believe at this point it's a bad decoder, just doesn't fit well enough without alterations to operate properly. I am not experienced in soldering and I really don't think a drop in should have to be hardwired anyway. As I said, I would be happy at this point to get the old decoder operating. This is the worst of both worlds at least before I had an operating engine now neither decoder will work. Papa
I've had to add a touch of solder to almost every decoder that I have put in my Atlas loco's. GP-38's -38-2s, SD35s, B-23-7s, U-23-Bs and a couple of others. Most use DN-163A0s. It's not hard. Since the decoder fits locos from several manufacturers it's probably hard to make one fit perfectly for them all. Had to do it with my Atlas MP-15s and walthers RS-2s. I prefer digitrax and see now that other decoder manufacturers are in the same situation.
Thanks for your reply. I can see , upon further review, that it is difficult to produce a circuit board that fits perfectly in all frames. I have since my last post managed to get the old decoder working and am now inclined to let "sleeping dogs lie" unless I can be convinced that the TCS decoder is a large improvement on the dual mode decoder. I had thought speed matching with other engines would be easier with the TCS decoder and that was my reasoning to change decoders in the first place. Now I have a new decoder that I paid for and am wondering if I should just take the hit and stay with what I started with. I may try to add solder or have someone else do it for me. My soldering iron is not the best and is in need of replacing the tip. Thanks again for your reply. Papa
I don't know this particular loco since I do not own one, but on other Kato and Atlas locos with drop-in decoders I often have had to take the frame tabs that make contact with the decoder and gently bend them or down slightly to get a decoder to fit properly. I usually use the edge of a screw-driver to either push them down or pry them up slightly while holding the loco by the frame. It's kind of a pain, but understandable given slight variations in manufacturing tolerances for both the thickness of the frame slots and decoder board. It COULD be that your original board is slightly thinner than the TCS board, and the very act of swapping boards meant that the frame tabs got pushed up enough that the original decoder no longer makes contact. TCS return policy is very good. I sent in a decoder with a minor problem and they sent me a new one, which I received about 8 days after shipping off the first. Adam
Papa, The problem you are seeing is not a decoder issue per say. The real problem is the spring contact motor lead design that Atlas uses. Different temperatures and almost any other action can cause the leads to not make good contact with the decoder. In one case, I had about 15 Atlas locomotives with decoders installed that worked fine on my home test track. I carefully pack them up to run at a show. One hour of driving the crappy roads in California, and low and behold, none of the locomotives worked at all. I had to pull the shells and carefully re-seat all of the decoders and then they worked. This happened with Digitrax decoders, TCS decoders and even the factory installed Atlas decoders It was from this experience that I now solder the motor leads to the decoder pads and have never had the problem again. I am not saying that there may not still be fitment issues like a little excess board material in front of the pads of the decoder, or possibly board thickness issues. But by an large, the spring contacts in the Atlas design are the major cause for the issues you are seeing.
Papa, Like others have suggested your problem is most likely where the decoder contacts the frame. I've had the same problem with TCS and Digitrax decoders as well. Before you ship the decoder back, or break out the soldering iron, or try to bend (or in my case break) the frame contact points try this. If you have a thin piece of styrene or any material for that matter, (eg. brass strips, toothpicks etc.) that you can make a couple of shims out of, try sliding them between the decoder and the frame contacts in order to get the decoder pads to make a more snug fit to the frame. If you get control of the lights but the motor still doesn't run then you'll have to adjust the motor contacts. If that still doesn't work then maybe you have a bum decoder. It happens sometimes and like others have said TCS is good about exchanges. Don't give up and just go back to the crummy dual mode decoder that came with the locomotive. IMHO they suck!! You'll love the new decoder expecially if you get a programmer like Decoder pro. Brian
Thanks again to everyone for your help/suggestons. I'm going to try and resolve the fit issue in one way or the other. If I put a dab of solder on the decoder pads I was afraid of too much heat being transferred to the board and thereby ruining the board, but it seems many have done this without that being a problem. I also may try the shim idea , do you shim it at the top once the decoders' installed? Seems if you put it under the decoder it risks foriegn material getting down to the motor if it comes out. In any case I have no reason to think it's the decoder and am quite sure it is just not making good frame contact as I have no lights. Papa
Thanks and H0 Scale, Too? I am new to DCC and this thread has some excellent "secret handshake" information that the manufacturers do not often publish. Thanks to all for the information. Does anyone know if this type of problem exists in H0 scale? I have not heard of this in any scale before. Thanks. Soldering connections seems like a good idea in any scale.
The trick is to put just a dab of solder on the tip of a small soldering iron with a pencil point tip then quickly touch the board with the iron to transfer the little bit of solder. do it at all four points of contact. that small amount of heat won't damage the board.
I've just fitted a TCS ASD4 to a Trainman GP15-1 and I used small strips of 20thou styrene to tighten up the contacts and fitted them on the top after the decoder was fitted to the frames. I chamfered the ends of the styrene strip to allow an easier fit into the space. I also noted that Atlas now seem to be using small spring clips on their light boards to overcome the contact problems with boards in the frames. I would have used these clips but they are just as difficult to handle as MT coupler springs and I lost a couple. :tb-biggrin: I haven't checked the Atlas spares list but they might sell these small clips separately which would make decoder fitting a lot easier, Jim.
I am not experienced in soldering beyond soldering two wires together. Not sure if it is my iron or what, but when I try to do it all I get is a "small ball" of solder that then just rolls off the pad or if it does adhere it is too much to then install into the frame. Also it seems if it is loose connection if I wiggled the decoder at should at least get lights to flicker wouldn't I? The only decoders I have installed in the past are Digitrax and haven't had a problem with them, so I don't know if there is just a difference in the thickness of TCS decoders or what. At this point I'm probably looking into trying a Digitrax and see if that works, but I doubt if I can send this one back without getting an exchange for the same decoder which at this point I don't care to have the same decoder as I suspect I'd have the same problem. Papa
A few months ago in a thread or two about soldering Leo Bicknell made some comments about what a difference a good soldering iron made. Someone else posted a link to this deal, which I ended up buying, with a couple options for tips, including 1/32" pencil tip. Still can't really believe what a difference it made. I could not have imagined doing decoder work with the equipment I previously had. I've done a couple TCS-CN decoders now, and installed a surface mount LED in the nose of an IM tunnel motor. I can easily imaging tackling more difficult fare. Yes, you still have to be skillful and careful, but with some things the right equipment is the difference between a job being possible or not. $40 is a pretty small price to pay to be able to actually solder decoders with ease.
I should try a better soldering iron like the one you posted some day. I do most everything with either a Radio Shack 15W and a Radio Shack 40W. I seem to just instinctively know which is better for each project. I don't have an easily defined system. That looks like a nice setup. Another thing that may help reduce the solder balling up problem is to use a little bit of flux. In a situation like what you described, Papa, where the solder balls up and doesn't go where you want, I will often take a cotton swab or similar small dabber and put just a touch of soldering flux on the thing I want to solder and that helps a lot. It doesn't take much at all.
Papa, it's likely what others have pointed out - wither poor contact to frame, or poor contact to the motor tabs, or both! I have 20 of this type of decoder in use, mostly TCS, amd only a few have shown these symptoms. The board thicknesses are probably different between each manufacturer, and the factory boards, by only a few thousands of an inch but that's enough to cause problems. I should note this is not a TCS only problem as others have had the same with Digitrax and NCE in the past. I have tried the solder to pad fix several times and had differing results as the gap in the frames have been slightly different from model to model and it may require too thin a layer of solder for you to apply easily. The suggestion made by JimG to slip a thin piece of styrene between the board and frame has worked for me as well. Also, make sure the motor contact strips align with the pads on the decoder and are flat as you can make them, and not touching the frame when the decoder is in place.
Well, I did finally get solder on the pads(one had a little too much) and tried again to install the TCS decoder. It seemed tight enough to at leas make contact and still no lights. Decided to return the decoder for refund and am wondering if it was bad decoder all along. I have installed other decoders and not had problems before, but can't guarantee it was still not making good enough contact, but also feel if you can wiggle the decoder you should get blinking on the lights anyway even if not tight enough for operation. Papa
I've just found out that the small clips that Atlas are using to make good contact between light/decoder boards and the frame sides are called "PCB CONTACT" with a part number #480030. I can't find them in the Atlas Online Catalogue but I've emailed their parts people to see if they are available separately. Jim.
Jim, when you get some information I would be very interested for future . My other decoders have all been Digitrax. Not partial in anyway it just turns out that's what I have installed in other engines. I think I will try a Digitrax and just see if I have better luck. Or, I could just keep the dual mode that's in it for now as it runs fine with it. Just thought for speed matching ect. it might not be best. Thanks, Papa.
