Have an Atlas (old) SW7 that I'm trying to convert to DCC. Isolated motor, temp installed decoder, programmed long address, but won't run. Tried running with direct dc to new motor connections, is okay, though rough. Is it possible that motor is not compatible with DCC? Need DCC CV setting? Remotoring? If so, what to use? Atlas SW7 problem by Doorgunnerjgs posted Jan 24, 2017 at 4:03 PM
Hi John I would suggest you run the motor on DC for about an hour to clean up the commutator and brushes. Once running smoothly, try the DCC decoder. What is the decoder current capacity, the motor looks pretty hefty from the photograph. Also the starting current can be much higher than the running current, even unloaded. Is the decoder or DCC Commander flagging a short circuit and shutting down?
Hi John, Are you positive the long address took? Did the decoder ever work on address "3", or did you ever tgest it? Did you program the long address using programming track mode...or program on the main (POM)? FWIW, initial addressing should always be done using programming track mode. If there's something wrong with the wiring then it's less likely to fry the decoder. Using POM mode subjects the decoder to full track voltage. If something is inadvertently shorted then...*poof*. I would first try address "3" [default] - just in case the long address was never programmed. It happens sometimes...
Thanks, programmed on the programming track, never checked it again. Will do that now! First will try short address 3. I should know better than to ASSUME anything! Was in IT for 40 years as programmer/systems analyst/project lead. Would think I would know better.
Well it was a good idea, but no joy. Checked on the programming track and long address was set, put on regular track and won't work with either short or long address. May break down and get a new motor for it. (Probably would be best anyway.)
It is not shutting down or indicating short. Don't know how much the decoder is capable of. I noticed that when running on DC, it took quite a bit of "throttle" to start it running.
Hi John, You said that you "checked on the programming track". Were you able to operate the locomotive on the programming track with either the short or long address? It still could be a bad motor...or the motor just needs some TLC (lubing) and break-in time. I recently installed a TCS decoder in a brass H20-44 switcher. It had never been run before so it was a bit sluggish/hesitant at speed steps 005 or <, which required an occasional push to get it going again. After about 45 min. of back 'n forth at various speeds on my programming track, she'll now do 0.25sMPH at speed step 001. How well did the SW7 motor run on DC before converting it? Also, what decoder did you install?
I would still run it on DC for a period. When running on DC, is there a ring of sparks running round the commutator. I have had this happen on brushed motors after prolonged periods of slow running. Ron
Will try running more on DC tomorrow, haven't run this on DC for years. When I hooked up the DC powerpack to test the motor, it ran rough and took a lot of throttle to start. The decoder is the NCE D13SR which I have used successfully several times. When I checked it on the programming track, only looked at the settings and confirmed short address 3, long address 113 and long address active. Thanks for all the suggestions.
By the way, it does not even try to run on DCC, even when turning the motor manually (finger power!).
If you haven't run this motor in years, John, then there's your issue. Whatever light oil that was on the bearings is probably pretty dried or non-existent. I would lightly lube it with some Labelle #108 oil and let it run for a several minutes to see if that improves things. You may also want to consider cleaning and re-lubing your gears.
Well, after rewiring to temporarily run as straight DC and lubricating the heck out of it, two things seem evident. First it is apparently drawing a lot of current. Small power pack shut down after about a half hour of running and had to cool down before running again. Second, the torque sucks. Was running the engine on its side to emery board the wheels a bit to remove crud and could barely apply pressure without it slowing down to a stop. May try to DCC test it again, but I think remotoring is the only solution. Have to wait until my next VA check to get one. In the meantime, I will need to research what motor to replace it with which, of course, requires checking shaft diameter and over all length. Creating a mount for it will also be necessary. If I didn't REALLY want to add this to my stable, it would be a waste of time and effort! lol
Yep, sounds like you have a tired pony there, John. A couple of things. First, you may want to consider investing in a good MRC power pack (e.g. Railpower 1370) at some point. It's simple and utilitarian but outputs a much cleaner and regulated current than a cheapy power pack. I picked up a couple of them on eBay for $20-$25 each. Now that I've converted to DCC I use them primarily for lighting and testing. Second, the emery board will remove crud from your wheels but will also scratch the surface of the plating and, thereby, cause your wheels to pick up crud even quicker. A inexpensive bottle of 91% rubbing alcohol can be obtained from your local pharmacy for $1-$2. I use q-tips to apply it directly to the wheels. Just be careful about getting any of it on the shell because it will ripple the paint. There's also a "paper towel method" that works well, too. For re-motoring, be sure to check the NorthWest Shore Line (NWSL) website. They can point you in the right direction and also help you with mounting, drive shaft coupling and/or gear replacement, etc. I used one of their coupler kits to replace the old rubber hose on the drive shaft of a Walthers SW1. It's worked great. The replacement gears helped, as well.
