Earl Bathurst Posted August 1, 2012 Share Posted August 1, 2012 Hi Got some chips in some of my locos but dont seem to get smooth acceleration. I got NCE power cab and when i got for example from notch 2 to notch 3 its a bit jumpy and dont get a smooth acceleration like i want, The notches only go to 28 so taking that its on 28 speed steps how do you get it to 128 speed steps? Also starting voltage by increasing that will that give you smoother acceleration? Hope someone can help Scott Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted August 1, 2012 Share Posted August 1, 2012 You want starting voltage as low as possible, set so that the motor only just turns over on speed step 1. Try higher values in CV's 3 and 4 to smooth out the step to step transitions in acceleration and slowing respectively - works whether using 28 or 128 speed steps. You will have to read your NCE manual to see how to change to 128 steps, unless some kind user of this system happens along with an answer. You could edit the title to show 'NCE 128 steps?' as a subtopic which gives this aspect a little more visibility. Link to post Share on other sites More sharing options...
HLT 0109 Posted August 2, 2012 Share Posted August 2, 2012 Scott, On the Power Cab handset, the button 2nd from the right on the bottom row reads "28/128" and "F12". Each press toggles between 28 and 128 speed steps. If you press Shift and the same button you get function 12. Harold. Link to post Share on other sites More sharing options...
250BOB Posted August 8, 2012 Share Posted August 8, 2012 Hi Scott, Tell us what chips you are using....there are chips and there are chips, some are better than others. Bob Link to post Share on other sites More sharing options...
Earl Bathurst Posted August 9, 2012 Author Share Posted August 9, 2012 HI I have some Bachmann a tcs and a zimo. I have the tcs in a Bachmann 56xx and on very slow speed it doesnt run too smooth or as smooth as i likie becuase the layout im building at the moment is only a small shunting plank and needs slow speed. WHat can i do different? Scott Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted August 9, 2012 Share Posted August 9, 2012 Can you test the loco without the decoder on a basic DC controller to see how it runs without the help of any back EMF? I give all my loco chassis at least an hour of gentle trundling about back and forth before a decoder installation, even if they come out of the box really sweet running. Noting that you have only a short 'plank' layout, what you need for this is a circle of set track which can be set up at need, and a very basic DC controller. The intent is to have the model running as sweetly and freely as possible so the decoder isn't having to compensate for mechanical deficiencies. Steam model chassis often take some time to settle down to being really smooth at low speeds, the rod coupling of the axles does mean there are often slight inequities in the drive line, and these show up most at low speed. Link to post Share on other sites More sharing options...
Earl Bathurst Posted August 9, 2012 Author Share Posted August 9, 2012 Thanks for the advise the locos i have here ready have all been run in and on dc i get really smooth crawling speed but dcc i get this bit of a jerk when crawling Link to post Share on other sites More sharing options...
Suzie Posted August 9, 2012 Share Posted August 9, 2012 Are you having trouble with the Zimo fitted loco? Link to post Share on other sites More sharing options...
brossard Posted August 9, 2012 Share Posted August 9, 2012 If the loco jerks at low speed or has jackrabbit starts it could be that the Back EMF is not working correctly. The first thing to do is to remove the capacitors from the motor and see how things go after that. If you still get jerky running, BEMF could be set "too tight", try backing off the BEMF settings. John Link to post Share on other sites More sharing options...
Earl Bathurst Posted August 9, 2012 Author Share Posted August 9, 2012 No problme with Zimo I think it could be the resistors someone else mentioned cutting 1 side of the crsistor wire. How do the resistors interfere with the dcc? Link to post Share on other sites More sharing options...
Suzie Posted August 9, 2012 Share Posted August 9, 2012 The Zimo is a much better decoder than the others and usually works pretty well straight out of the box without configuration, so you will probably need to do a bit of tuning of the back EMF if the TCS and Bachmann decoders have it. To get the back EMF to work properly you will need to remove the motor capacitors and bypass any inductors in series with the motor. There should not be any resistors to worry about. These components restrict the high frequency signals that the decoder uses to control the motor, that is why they have to go. The decoder contains other components that perform the interference suppression that they were there for. Link to post Share on other sites More sharing options...
newport_rod Posted August 17, 2012 Share Posted August 17, 2012 Scott, I've sent a PM with some notes on configuring decoders to optimise smooth running. Cheers Rod Link to post Share on other sites More sharing options...
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