Steamy Gramps Posted March 27, 2014 Share Posted March 27, 2014 Hi I have just had a new decoder (with sound) fitted to my Hornby Black B5. Movement is very jerky during start up and stopping. It is as if contact is poor until it is running at full speed. My other locos run fine so I don't think it is the track. I will refer it back to the people who fitted the card but wondered if anybody might be able to say what it might be in case I can easily sort it myself. Thanks Link to comment Share on other sites More sharing options...
idlemarvel Posted March 27, 2014 Share Posted March 27, 2014 magfan said: two cvs control this start up and stopping cv54 and 55... Thanks for the info. As I understand it CV 54 and 55 are in the range 47-64 which are manufacturer unique according to NRMA list. Will your suggestions work with any decoder? Thanks, Dave Link to comment Share on other sites More sharing options...
Fishmanoz Posted March 27, 2014 Share Posted March 27, 2014 They are certainly in the manufacturer-defined range but seem to have commonality across a number of brands of decoder. Link to comment Share on other sites More sharing options...
Fishmanoz Posted March 28, 2014 Share Posted March 28, 2014 Just checked, not supported by Sapphire, only CV50-53. Link to comment Share on other sites More sharing options...
Fishmanoz Posted March 28, 2014 Share Posted March 28, 2014 And Sapphire CV52 different too, being Asymmetric DCC configuration with values from 0-7 only. Link to comment Share on other sites More sharing options...
Raven_Electric Posted March 28, 2014 Share Posted March 28, 2014 I've just made a comment on PID Controllers on another thread in DDC and such controllers have universal applications and are what are being discussed here. Magfan, your theory on the cause of variability on different DCC systems, with resulting "kangerooing", is interesting. The "Controller" (in DCC terminology) doesn't control your loco at all of course as at all times it is under the control of the decoder, the controller merely sending it "commands" to change the current state of things to which, dependent on the sort of day it is having the decoder may decide to respond. So why do things change when moving for one DCC setup to another? Well, the "Controller" DOES control the square wave voltage and reversal timing for encoding the digital signal. The later will tend to be either right or wrong and there are other variables. slew etc, but the voltage is the main one and tiny voltage variations between each DCC system could prove your theory spot on and would require a tweak to the CV PID settings unless the Controller has a provision to calibrate/change the voltage. I imagine there are few that do as most will leave it to whatever voltage the transformer sends but in that case you could test your theory by using the same transformer on both systems in turn. Link to comment Share on other sites More sharing options...
Raven_Electric Posted March 28, 2014 Share Posted March 28, 2014 DCC of course. Being DDC, (DAFT DEGENERATE CHUFFER) is another control problem that leaves me wondering where I put things down most days. Link to comment Share on other sites More sharing options...
Gregd99 Posted March 28, 2014 Share Posted March 28, 2014 If you are getting jerky movement it is also worth having a look at the Back EMF cut-out CV. I had a class 20 that was very jerky until I disable the back-emf cutout.... now smooth as silk. Link to comment Share on other sites More sharing options...
Graskie Posted March 28, 2014 Share Posted March 28, 2014 I have a few jerky movements nowadays. Link to comment Share on other sites More sharing options...
Graskie Posted May 9, 2014 Share Posted May 9, 2014 Magfan, following my trite comment above, I have just used your suggestion for resetting CVs on a jerking loco at low speed, and it worked perfectly. I can't thank you enough. Link to comment Share on other sites More sharing options...
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