HELP! DCC loco gone crazy!

[tigerthelion]

Please help!

I have three locos that I use as a consist when all of a sudden one of them caused a short circuit and everything stopped (I use the Dynamis system). I quickly pinpointed the loco and removed everything else from the tracks. As soon as I hit the stop button again to resume power, it took off at full speed and will not respond to the controller at all! What can I do to regain control of my loco? I'm not very experienced with decoders and don't know what to check for! Thanks

[Flare]

Try resetting the decoder to factory settings.

On Bachmann locos this usually means changing CV 8 to 8.

If you don't have stationary rollers, make a loop of track to hold the loco.

[jward]

When a DCC locomotive does this, it is often caused by a dual mode decoder going into DC mode. The decoder thinks it is running on track controlled by an analog power supply, and thus will respond to changes in track voltage. DCC, however, uses a constant voltage on the tracks, at the upper end of what an analog power pack can deliver. Thus the locomotive takes off at full speed.

The good news is that this feature, called analog conversion, can be disabled by reprogramming cv29. The bad news is that cv29 also controls a lot of other things as well, such as normal direction of travel. Figuring out what value to program can be complicated.

There is a conversion table on the digitrax website that lets you enter the features you want, then calculates the value to program into cv29. Hope this helps.....

http://www.digitrax.com/support/cv/calculators/

[tigerthelion]

I tried reprogramming the loco on the main track, and it completely ignores anything I try and races around the layout at an unbelievable speed.

I tried reprogramming on the service track and its hard to do because I have to use one hand to keep it in one place (my service track is only a couple feet long and wired seperately from the layout) while using the other hand to use the dynamis. It's a NCE D13SRJ decoder and the instructions says to change cv 30 to value 2 to reset it to factory settings. The train stops racing; vibrates once, pauses for a second, then takes off racing again. If I hit the stop button the train will stop however it wont allow you to program while stopped. The reprogramming does not take effect and the train takes off racing again. I also tried resetting the cv 8 to value 8 but it didn't work. I'm stumped! Thanks for your help guys, I appreciate it. Cheers!

[tigerthelion]

Thanks for the info! I've been trying repeatedly for the last 30 minutes but its not working. Keep you all posted. Cheers!

[tigerthelion]

Three days of trying to reset the decoder and it just wont work! What should I do next? Thanks

[Flare]

Two things come to mind.

You can replace the decoder, or if it's new loco you can ask if the warranty covers this.

[tigerthelion]

First, a big thank-you to you all for responding!

Its a NCE decoder in an Atlas C424 loco that I bought used on ebay about 6 months ago and worked perfectly until I experienced a short circuit. I've tried resetting the decoder's CV many, many times (on a programming track). As soon as I place it on the track it takes off without power being turned on! Ive never seen it before. Looks like I will be replacing the decoder.

Thanks again!

[Trainman203]

This kind of thing is "exactly " why I "never" buy a used locomotive, period, unless it is from a friend.

http://www.worldwidewords.org/qa/qa-pig2.htm

[Searsport]

Hi, in extremis you can remove the decoder from the loco and re-program it on the bench, which is where it was programmed in the first place. Google to find out how.

Good luck,
Bill.

[Trainman203]

Put a Tsunami 2 in.  Your troubles will be over.