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Train that won't stop

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  • Member since
    April 2009
  • From: Staten Island NY
  • 1,734 posts
Train that won't stop
Posted by joe323 on Wednesday, April 19, 2017 6:30 AM

One of my locomotives with a digitrax decoder won't stop unless I cut track power.  I did a factory reset but still didn't stop. It responds to all other commands.  Any ideas?

Joe Staten Island West 

  • Member since
    May 2010
  • From: SE. WI.
  • 8,253 posts
Posted by mbinsewi on Wednesday, April 19, 2017 6:45 AM

Reminds me of an Atlas with a Digitrax decoder I got off of Ebay, ran great for a time, then it started acting weird.  It would loose it's address, then the next time it would run with almost no speed control, then the next time it would run great, then back to address issues.

I put up with it, ran it when it was running good, and did a lot swearing at it when it would.  I lost count of how many times I reset it.

Finially started to research it, and found out the DH121 decoder that it had was retired in 2002.  This was 2014.  I gave up, plugged in a new decoder, double checked the wiring, and problem fixed.

For me, worth the $20.

Mike.

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Wednesday, April 19, 2017 6:51 AM

Make sure CV3 and especially CV4 are 0. Huge momentum values may make it appear as if the loco will not stop.

If there is a reset for the command station, try that as well. Speed 00 is speed 00, power is supposed to cut going to the motor.

Does it start up stopped, or does it take off as soon as power is applied? If it just takes off, the decoder is probably blown.

                                --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Wednesday, April 19, 2017 7:14 AM

Tell us more about this decoder and its performance.

Which Digitrax decoder is it?

When you say that the loco won't stop, will it slow down or just keep running at the set speed?

When you say that it will respond to other commands, such as?

Is this a newly installed decoder or have you had it installed for a while?

Any recent derailments, shorts, or other adverse happenings with this loco?

Rich

Alton Junction

  • Member since
    December 2001
  • From: Northern CA Bay Area
  • 4,387 posts
Posted by cuyama on Wednesday, April 19, 2017 9:23 AM

I don't recall if Digitrax decoders default to automatic analog conversion (DC) mode (CV29, I think). I have seen this occur a few times with older Digitrax decoders that interpreted a slightly rounded DCC signal as DC and took off. 

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Wednesday, April 19, 2017 10:51 AM

 Pretty much all decoders default to DC operation enabled on reset - default value of CV29 is 6.

                          --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    April 2009
  • From: Staten Island NY
  • 1,734 posts
Posted by joe323 on Wednesday, April 19, 2017 11:37 AM

Thanks everyone I will open the hood on the offending loco (an Atlas GP38-2) when I get home, as I need to confirm the model number of the decoder and go from there.  

The loco responds to direction control and acceleration but does not seem to decelerate when I dial back the speed on ny powercab.

Joe Staten Island West 

  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 13,892 posts
Posted by wjstix on Thursday, April 20, 2017 10:53 AM

I'd try setting CVs 2-3-4-5-6 all to zero and then try it. That at least will eliminate it being a problem with a CV setting (although that should happen when you do the re-set, but decoders can do funny things.) Maybe make sure CV66 and 95 are at their default settings, usually 128.

Stix

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