I recently purchased an Atlas C420 on a popular auction site. It was used and bought it for a good price. The listing stated that the loco ran poorly or intermittently probably due to it having a DCC board and tested on DC track. About the best I can get it to do is light up. I have partially dismantled and clean and lubed the trucks and electrical wipers. Still won't budge. I'd appreciate any advice on possible next steps. Thanks in advance, Dan
I don't know anything about DCC, but I'd start with completely removing the motor and trying to power it up separately. If it runs smoothly, you'll be able to better isolate a problem with the wiring or the DCC board.
Dan, A quite common problem with any of the Atlas / board decoder models is that the contact tabs sticking up from the motor are not make good contact with the bottom of the board. The fact that you got lights but no movement would strongly suggest that is the problem with your C420. I've always hard wired this connection to make things reliable. The newer decoders have slots for those contact tabs to fit into and this helps.
If it has a drop in decoder sometimes the tabs that hold the decoder in place are gapped a little wider than the decoder board is thick. To make the board fit tighter, you need to put a SMALL drop of solder on the decoder board that corresponds to the mounting tabs that are loose. Might be one, or it could be all four. See how tight they fit, add a drop of solder on the board as needed, then file the solder you just put on down to where it will fit snugly into the tabs. Doing this, and following Brad' s suggestion above, should end any electrical contact problems with the decoder.
If your loco's problem in the motor contacts, another fix, if you don't want to solder them, is to clean, adjust them correctly and apply a contact conditioner to keep them from tarnishing down the road. I use Deoxit and have Atlas locos that I installed decodes in years ago, some of the first Atlas DDC ready locos available, and haven't had a single problem.
Remove the motor and connect the contacts to a 9V battery to see if the motor spins. If it does, something is not connected on the motor side of the decoder. I would solder those connections to take out the guesswork.
Dan, The Atlas decoder board can be removed and a 9v battery touched to motor tabs to verify that the motor runs on dc. You do not need to remove the motor. I think that Atlas used a NCE N12AO for the decoder in that model. If so there are a couple of slots where the motor tabs contact decoder, it is possible to fish motor tabs up into these slots and bend the tabs over after the decoder is seated back in place. Doug
The other reason this may not run as well as it should is the factory DC board is thinner than previous ones. Our friends at Atlas added removable clips to the board to get it to fit the frame and provide reliable contact. I'd check the DCC board to see if they were transferred over. I missed it on mine and when I figured it out it ran perfectly Hugh
Thank you all for the suggestions! I look forward to trying them and seeing what I can figure out. I'll let you know how it goes. Dan
Well, I disassembled the loco. I put a little drop of solder on each of the four contacts on the DCC board to insure contact. I cleaned most of the copper that would be making contact. I used a 9V to test the motor and it spins just fine. However, reassembled and on the track it only lights up. A little wisp of smoke came up when I throttled up the power supply. Still won't budge under its own power. Any thoughts? I haven't given up. Thanks, Dan
"A little wisp of smoke came up when I throttled up the power supply" Well you tested the motor and it was OK, so, IMO it sound like a motor contact was touching the frame and now the DCC board is toast.
Not having any other experience with disassembling motors other than this one, can anyone give me an idea of where to look for a short between a motor contact and frame? Since I am running DC, would I be able to replace the DCC board with the Analog board from the Atlas sight? Many thanks! Dan
The part number for that board is 2600-X002. That board is common and used on several Atlas N Scale models. Here is a listing for them on ebay. It may also be available from Atlas.
