Jackrabbit start

[jwilliam33]

I'm using a PowerCab controlling a P2K GP30 with an Atlas decoder and can't get the thing to stop jackrabbit starting.  I've changed CV2 to 0 and CV8 to 8. I also cannot get the headlight to full brightness, seems to be dim at all times.  Suggestions?  Help!!

[jbinkley60]

jwilliam33

I'm using a PowerCab controlling a P2K GP30 with an Atlas decoder and can't get the thing to stop jackrabbit starting.  I've changed CV2 to 0 and CV8 to 8. I also cannot get the headlight to full brightness, seems to be dim at all times.  Suggestions?  Help!!

A P2K with an Atlas decoder ?  That seems a bit odd.  Anyway, the jackrabbit question comes up every few weeks.  The solution is to turn off analog mode in CV29.  Here's the latest thread on the subject.

http://cs.trains.com/trccs/forums/t/157747.aspx

 

[jwilliam33]

Thanks but CV 29 is set to zero.  It doesn't run away from me, just starts with a jerk and then responds to throttle control as it should.

[jbinkley60]

jwilliam33

Thanks but CV 29 is set to zero.  It doesn't run away from me, just starts with a jerk and then responds to throttle control as it should.

If you are using 4 digit addressing on your  locomotives set CV29 to 34 or 35 (depending on which is the proper direction for you).  A value of CV29=0 is invalid.

 

[CSX Robert]

0 is not an invalid CV29 value. 0 means 14 speed steps, analog conversion off, forward normal direction of travel, and 2 digit addressing.

[rrinker]

Remains an issue unless the OP status edited that address. The loco will respond incorrectly if fed 28/128 from teh command station and it's set for 14. ALso the lights will not operate properly.

                      --Randy

 

[jwilliam33]

Well, I tried CV 29 to 34 and no luck.  It still jumps for a short distance and then responds properly to all throttle controls from there.  Lights are still dim as well.  Thanks for all the help but I guess I'm looking for more to figure this one out.

[CSX Robert]

jwilliam33

'm using a PowerCab controlling a P2K GP30 with an Atlas decoder and can't get the thing to stop jackrabbit starting.  I've changed CV2 to 0 and CV8 to 8.

The first thing you need to do is find out for sure what decoder is in it(an Atlas decoder in a Walthers or Life-Like engine would be mighty unusual) and reset the decoder to it defaults. By reading CV8 and CV7, we can tell you who made the decoder and probably what version it is, and then we can determine what to do to reset it. Programming CV8 to 8 does reset Digitrax decoders, but that is not true of most others.

[selector]

Could this be a torque compensation, BEMF, or a dither problem?  Some decoders have a "kick start" minimum voltage setting.

Jus' thinkin'....

-Crandell

[jwilliam33]

Manufacturer 34

[maxman]

jwilliam33

Manufacturer 34

Are you sure?  According to the NMRA manufacturer 34 is Aristo-Craft.

http://www.nmra.com/standards/DCC/mfgnumbers.html

[jwilliam33]

Sorry, read wrong spot.  It reads manufacturer 11 (NCE) version 34.  I don't know why it reads an NCE decoder as I did not install one but that's what the power cab reads.

[maxman]

Did you install a decoder, or was it installed when you got the engine?  It's likely that someone installed a decoder in the engine, quite possibly an NCE.  I think that you can get an NCE decoder that would plug into the light board that originally came with the engine.  I don't think that Atlas makes a plug-in decoder, so the only way an Atlas decoder would be in there would be if someone replaced the original lightboard with an Atlas replacement.

What lead you to believe that there was an Atlas decoder in the engine?

Oh. Check the instructions that came with the model.  There are some models that require you to change the lightbulbs to a different voltage rating if a decoder is installed.  I don't know if this is one of them.

[CSX Robert]

jwilliam33

It reads manufacturer 11 (NCE) version 34.

The jackrabbit starts possibly could be caused by the torque compensation kick rate and kick strength(CV's 116 and 117). To reset the decoder program CV30 to a value of 2 on the programming track(in other words NOT in OPS mode). Here is the manual for the NCE P2K-SR decoder.