Atlas Nscale SD60 Short Circuit Problem

[Herc Driver]

Hi Guys,

I have two Atlas Nscale SD60 units, both are "Decoder Ready" as listed on their box. I bought two new Digitrax DN163A1 decoders that are listed as the correct choice - according to Digitrax.

I installed a Digitrax DN163A1 decoder in an Atlas Nscale SD60 and things didn't go well. The installation was straight forward, good electrical contacts made, and the decoder programmed on the programming track.

The fun started when I placed it on the layout. Nothing. No motor control, no lights. I double checked the engine connections, made sure the decoder was seated correctly between the frame halves, but still nothing. No movement, no light control, nothing except a quick rear light flash when the engine was first placed on the rails.

So I removed the dcc board and reinstalled the dc board...thinking it might be a bad board. When I placed the engine back on the tracks with address 00, the engine burst to life and surged forward and abruptly stopped, then surged again, then stopped. All the while, my Digitrax Zephyr controller was showing a short circuit indication. When I deselected the "Power" button to remove power from the rails (I thought), the engine surged forward at a high speed and without any control from the Zephyr. I lifted it off the rails. Since I've never seen this problem before, I repeated the procedure to see if it would do it again, and it did exactly the same thing. I tried the other Atlas SD60 unit (with its dc board still installed from the factory) and it did exactly the same thing.

I next tried to determine whether the Zephyr was bad, or there's something with these engines. I removed the strange acting SD60 engine, and placed a decoder equipped engine back on the rails, and it worked fine. No problems, no shorts. I chose another Atlas dc engine (no dcc circuit board installed - just the standard factory dc board), one that I bought about five years ago, and it worked in the basic dc mode on address "00" without any problems.

I checked the track, there are no pieces of metal "shorting" the rails. I removed all the other engines from the rails and tested only the SD60 unit, and it still had the same crazy problem. I don't have any other throttles hooked in the "jump" port of the Zephyr, just the basic unit by itself is supplying power and running the dcc operation. There's absolutely no problems running any other dcc equipped engine, or mixture of dc and dcc engines.

My only guess is there's something with these SD60 units. They were bought in different stores, in different states, but both have "1998" stamped into the frame. It is a split frame, with plastic inserts dividing the frame at each end where the frame screw is inserted to the nut. The motor's electrical leads touch the dc and dcc board at the correct spot.

I suppose there could be a problem with the Zephyr dealing with these particular units, but find that hard to believe. I had been running the unit for about 30 minutes without any problems just prior to this decoder install. And it runs other dc-only engines without problems.

Anyone have clue what's going on here? I'm stumped. I've tried to place the problem engine back on the rails this morning, and it did exactly the same thing as last night when I first encountered the problem. I don't know what's going on, but my guess is there's something short between the frames that I haven't discovered yet...though...I'm still in the "learning mode" of dcc theory and operation, so maybe there's a bigger problem here with the Zephyr that I don't understand.

Thanks for the help guys!

[eightyeightfan1]

I'm not a DCC guy. But if they are older models, they might not be "DCC ready" I have no idea when they started making the N scale locos DCC ready, but I'm pretty sure it was after 1998. That could mean the the motors aren' t isolated from the frame. Like I said. Its just a guess.

[woodone]

I ran into a short on a Kado Mikado after doing a DCC with sound install. I could not find a problem any where. I have done many of these locos and feel I know them well. This one was different!!! After removing all of the decoder wiring I checked each and every wire- All check OK. Then I checked the frame halfs--I had an electrical path between the halfs? How can this be? I could not find any metal between the two halfs, but still had conductivity between the two??
I started to remove the screws that hold the frame halfs together, and when I lossened the rear screw the conductivity would go away. Tighten it up and the frame would become one piece of metal. After removing the screw and it mating nut I found a very small sliver of metal that had come from ( who knows where) on the screw, the head of the screw would make contact with this metal sliver and press it to the other frame half. Cleaned the screw and the frame halfs were no longer showing any conductivity. The short was gone AT LAST!
It is the small things that get you somtimes.

[Steamtrains]

When locos go "crazy" on the track, it's a sure-fire indication (with the Zephyr) that you have a short somewhere. If everything else works fine, it's got to be in the locos. If you've got a multimeter it should be easy to track down. Check conductivity from the wheels to the opposite side on the frame, and between the frame and the motor leads.
Good luck..!!

[Herc Driver]

After lots of time spend searching the engine for the problem...I noticed one of the motor contacts touching the inside of the frame when placed into position beneath the dcc board. After carefully threading the needle as it were, by inserting the motor contact through the insert point on the circuit board and then straightening out the contact metal so it didn't touch the frame, and isolating the frame from the motor with kapton and electrical tape, the engine finally works. WIth the other SD60, I repeated the whole procedure and it too now runs with the dcc board installed. I'll try to redo my tape fix on the first engine and concentrate on getting the motor contact strip bent just right...but of course you can only do that after the board is installed and in place, so there's just about no room to work in. Ah well. I'm happy for the success, and learning a bit more about decoder installations. But sometimes I really wish "DCC Ready" really means "ready".

[Russ Bellinis]

What you need to look for when buying a locomotive is "dcc installed." "Dcc ready" only means that the locomotive is ready for you to install the decoder. Manufacturers do that so that they can sell the locomotive to someone who is going to use the locomotive on a dc layout, but so that someone could pt a decoder in and run it on a dcc layout. I think Litchfield Station and Tony's Train exchange will install decoders for a fee on customer locomotives, but I don't know what they charge.

[Herc Driver]

I've about...oh...I dunno...about thirty engines that I still need to install a dcc board in. Most are the "DCC Ready" type where I'll need to trim a little here and there to make them fit. I've installed about 20 decoders so far I think, but these two SD60 units were the most problematic. With the new engines I currently have on order, I just bit the bullet and ordered them with the dcc already factory installed. I don't mind doing the installation...but it sure would be a bit easier on my time to have a few less to switch over.