I have an Athearn RS-3 that I equipped with a basic Digitrax decoder. Recently, I was using this as a test engine to work out problems with my auto reverser that I described in another thread. During this process, it was exposed to numerous shorts which occured when it bridged the insulated gaps at the entrance and exit to the reversing section. That problem has been resolved but I have noticed recently that occasionally, it continues to run after I shut off the trottle. My first thought was dirty wheels but I looked at that and it doesn't seem to be the case. I am now wondering if exposing it to all those short circuits may have cause slight damage to the decoder which prevents it from reliably stopping on command. Other than the stopping problem, all other functions seem to be working normally.
jecorbett I have an Athearn RS-3 that I equipped with a basic Digitrax decoder. Recently, I was using this as a test engine to work out problems with my auto reverser that I described in another thread. During this process, it was exposed to numerous shorts which occured when it bridged the insulated gaps at the entrance and exit to the reversing section. That problem has been resolved but I have noticed recently that occasionally, it continues to run after I shut off the trottle. My first thought was dirty wheels but I looked at that and it doesn't seem to be the case. I am now wondering if exposing it to all those short circuits may have cause slight damage to the decoder which prevents it from reliably stopping on command. Other than the stopping problem, all other functions seem to be working normally.
Ahh, the old DCC runaway problem. The fix is to turn off DC (analog) compatability mode in CV29. CV29 is an indexed variable and bit 3 (binary value of 4) is to turn this function off/on. Most folks recommend CV29 be set for 34 or 35, depending upon the direction of travel. This turns off DC compatability mode. The one downside is that you can't run the locomotive on a DC layout without turning this back on but it will fix the runaway problem caused by shorts.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
I would do, or ensure myself that, both recommendations are carried out. You must surely have a spurious value entered in at least one CV, and it has caused the change you see. But do verify both. Ensure that CV2, or V-Start, is reduced to the point where the loco just begins to creep forward when you assign the decoder speed step 1. Then ensure CV 29 is at 34 (for 90% of the cases).
As David suggests, you may have to play with CV 4 once more to figure out if its value is causing the engine to coast too long. If the engine behaves without changing CV 4, and after the two steps above, you may be okay, but it wouldn't hurt to zero the value and then assign it a new higher one to suit your desired operating characteristics.
-Crandell
Thanks, everybody, for the suggestions. I have to confess I will be entering a new world since I've only read briefly about CVs and have never even attempted to change one but it's probably time I learned how. I guess it's back to the instruction manual.