I drove myself nuts yesterday trying to figure out why my P2K GP38-2 - that had operated flawlessly 2 weeks ago - wouldn't respond to any throttle commands. I went thru each of the troubleshooting steps in the Manual, until the only one left was to check my CV29 settings. I thought to myself, "I never mess with CV29 - how could it possibly be that?" But for the sake of argument, I read the value of CV29 and it was...4?! (I had set it to 34 ~6 months ago.)
Restoring CV29 to its proper value solved the problem. My question is, What could possibly make a CV value spontaneously change like that, any ideas? It's a Digitrax decoder if that makes any difference.
-Ken in Maryland (B&O modeler, former CSX modeler)
Ken,
S**t Happens! I have seen the same thing over the years. One time we had a short(switch thrown wrong), and a Spectrum Doodlebug lost it's address. Re-program it and it was fine. I just went through a 'reset & re-program' session on my 30+ engines. I used Decoder Pro to 'look' at all the CV's and record them to paper. After the 're-program', I compared printouts and was amazed to see CV's I never touched with strange values in them.
I suspect 'electrical noise' on the track/bus may have been the culprit. This time I programmed tyhe decoders to 'DCC Only' and used the 'decoder lock' if the decoder has the feature. We will see how I fare over the next year. I have also had decoders that seem to 'lose' their address just sitting in the box. This happened to some early Digitrax decoders a number of years ago, and they have been replaced or sold off with the engine as I upgrade motive power. A friend has had the same thing happen with NCE decoders.
Jim Bernier
Modeling BNSF and Milwaukee Road in SW Wisconsin
Thanks Jim,
I suspected it was probably line noise. At least now I can be on the lookout for stuff like this, and it won't be such a shock next time.
Don't let anyone fool you---It is really the gremlins. Course, have also seen sunspots cause strange things.
This has happened to me from time to time, and why Decoder Pro (free download) is such a great value. I just place the locomotive back on the programing track; call up the Decoder Pro file for that locomotive; and re-write all of the CVs back to the locomotive.
Jim, Modeling the Kansas City Southern Lines in HO scale.
I have seen this happen when bit 3 on CV29 is not enabled. This is the analog conversion mode. This CV has a value of 4. If analog conversion mode is enabled (CV29 bit 3 is 0) then I have seen instances where pushing a locomotive over or it hitting a dirty spot on the track will cause it to go racing, CV variables to change etc. With analog covnersion mode enabled the decoder responds to DC and any change in DC from shorts, spikes etc. may cause odd things to happen. I've never had the problem with analog conversion mode disabled. I only use CV29 being set to 34 or 35, depending upon the direction of travel. Don't set CV29 anywhere between 4-7, 20-23, 36-39, 52-55. This might resolve the issue. It has for me.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
Full Moon, Sun Spots, Gremlins (1970s AMC product), fog or even rain inside of buildings. The loco with the scrambled brain does not even have to be the one that shorts. Happens sometime. Even with DC off in CV29. I had a loco go nuts on me at a show once. Turned out another module group member had the same address loco running on the other layout and the wireless throttles were cross talking. That was strange all of a sudden the whistle goes off and the loco moves all by itself until it rear ended the train in front. Stuff happens.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
locoi1sa Full Moon, Sun Spots, Gremlins (1970s AMC product), fog or even rain inside of buildings. The loco with the scrambled brain does not even have to be the one that shorts. Happens sometime. Even with DC off in CV29. I had a loco go nuts on me at a show once. Turned out another module group member had the same address loco running on the other layout and the wireless throttles were cross talking. That was strange all of a sudden the whistle goes off and the loco moves all by itself until it rear ended the train in front. Stuff happens. Pete
Yep, that often happens at shows when folks keep the networks at default. With Digitrax, folks should change the Loconet ID when going to shows. The default of 0 is just too easy to cause problems. I am sure other wireless systems have similar options.