Need some help here – I purchased an MP-15DC (N scale) earlier this year. It ran quite well on DC. As I was converting to DCC, I purchased a decoder from Digitrax (DN163A3) and installed in the locomotive. It worked wonderfully the first day. The next time I had time to “play trains” the loco would not respond to forward/reverse or speed commands, but light commands still worked. I removed the shell, and tried again, got intermittent shorts on the track and generated “smoke” from the engine. So I pulled the loco off, hot to the touch, shut everything down, and when I put the loco on a programming track, the decoder could not be resurrected. So thinking I did a really bad install, I put the DC board back in and the loco would work fine in DC mode (but with the characteristic DC operating on DCC hummmmm). Time passed, got a new decoder and installed being very careful to make sure the motor leads were lined up correctly, etc. Programmed just fine. Ran fine the first night on DCC and parked it in the roundhouse. Next time I ran trains (again a few days later) it started out fine although it had some intermittent behavior (I thought just maybe wheels dirty affecting pickup), then got some shorts because of the loco, then loco was not responding to speed or direction inputs (light commands still worked) and while no smoke, the loco smelled electrically hot. So, I have set the loco aside out of frustration. What should my next troubleshooting steps be? I recognize the warranty is still available, but am willing to do some more troubleshooting to narrow things down a bit more…….and to assure I am not the cause of the problem. Any insights and help would been genuinly appreciated.
Dave, Did you apply insulating tape on the frame sides next to the motor contact strips? Your experience seems very similar to mine with another Atlas DCC fitted loco which I had stripped down to do some work on the trucks and when I rebuilt it, it ran fine for a short while, then started operating eratically, then the decoder died. I found that one of the metal motor contact leads was touching one of the side frames which caused the death of the decoder. I applied insulating tape to the insides of the frame sides next to the motor leads when fitting a replacement decoder. It was only after that that I found out that this was a recommended process when working with Atlas locomotives. People also recommend getting rid of the metal contact strips and wiring the decoder pads directly to the motor brushes - this also gets round the problem of poor contact with the decoder. Jim.
Jim, I had not installed insulating tape since the instruction sheets had not indicated it was necessary. When I get some time to disassemble, I will check it out.
Dave, I reckon it really is a design fault with the Atlas locomotives. There must be a knack of assembling them on their assembly line which keeps the metal strips from touching the frame sides, but once we start doing work on the locos ourselves it becomes extremely difficult ot ensure that the metal strips don't touch the sides when we re-assemble. It would be interesting to know if Atlas do have experience of this problem when they QC their DCC locos. :tb-biggrin: Jim.
Dave I just had a look at the Digitrax website and the installation for the MP15DC and there is no mention of insulating tape. However, on an Atlas Dash8-40BW I cooked two decoders despite following all the instructions correctly, applying tape where indicated. Finally out of frustration, and on advice from my LHS, I used liquid insulation and applied it over both halves of the frames and this solved the problem. On two other Atlas locos I have put kapton tape in between the bottom of the frame halves to ensure no contact when tightening the frames. Therefore the solution may well be applying kapton tape to one side of the metal frame to ensure no contact between the two halves. Best I can think of. Wal
I own 4 Atlas MP15s and installed decoders in them. I didn't use any insulating tape because it's not needed. You do need to bend the motor contact wipers so when installed in the Digitrax board they do not touch the frame. You should also use an ohm meter to check for any short before putting the loco on a test track!
You might need to Blob it I had trouble with my MP15 maintaining contact with the flimsy contact poles to the decoder contact pads. MP15 Contact Poles DN163A3 Contact Pads So I blobbed them with solder and have a nice firm fit. DN163A3 Contact Pads with Solder Blob
