TheSnapper Posted February 27, 2019 Share Posted February 27, 2019 Zimo 645 in an O Gauge loco Without changing the gear ratio or wheel size(!), is there anything on the decoder other than CV267 that can be adjused to affect the Chuff Rate? I can't seem to get this one just right despite CV267=255. Or is the rate set inherently in the project? Tim Link to post Share on other sites More sharing options...
RMweb Premium Vecchio Posted February 27, 2019 RMweb Premium Share Posted February 27, 2019 (edited) Did you check if CV 268 is set to Zero? if not CV 267 doesn't work check also 354 if there is still a difference for very slow speeds. Edited February 27, 2019 by Vecchio Link to post Share on other sites More sharing options...
TheSnapper Posted February 27, 2019 Author Share Posted February 27, 2019 Thanks Vecchio, yes CV268=0 I have been adjusting CV267 OK, but run out of digits ! I have fiddled with CV354, but it doesn't seem to make any difference Wondering if CV57 may have any effect.....? Tim Link to post Share on other sites More sharing options...
RMweb Premium Vecchio Posted February 27, 2019 RMweb Premium Share Posted February 27, 2019 No, CV57 is about the control characteristics of your models motor. Did you try extreme positions as for instance CV267=1 (very fast) and CV267=254 (very slow) to hear if there is a change at all? Link to post Share on other sites More sharing options...
John K Posted February 27, 2019 Share Posted February 27, 2019 Hi Tim I use MX645s for most O gauge applications What is the loco and what motor /gearbox are you using. John K Link to post Share on other sites More sharing options...
TheSnapper Posted March 2, 2019 Author Share Posted March 2, 2019 John, Vecchio Sorry for delay in replying, I have been offline for a couple of days. I have tried extreme positions and there are enormous differences! Loco is a small tank 0=4-4T, motor is a Mashima 1833 by the looks of it. Gearbox is a single stage but no idea what ratio. I didn't build the loco, so I cannot change the mechanics. With CV267 = 255, it is just not quite slow enough. Tim Link to post Share on other sites More sharing options...
TheSnapper Posted March 4, 2019 Author Share Posted March 4, 2019 Chaps I think I have realised what the problem is. The decoder was supplied by "my customer", and it is for a larger loco - a 4-6-0. (I did express my concerns about its suitabvility at the time) It seems obvious that the larger loco would have a higher gear ratio & possibly larger driving wheels. The sound project would be tailored towards this. Does that make sense? The customer will have to live with it, or pay for a reblow......! Thanks Tim Link to post Share on other sites More sharing options...
RMweb Premium Ray H Posted March 4, 2019 RMweb Premium Share Posted March 4, 2019 Is a CV value of 255 treated significantly differently than a value of 254? I recall there are several CVs where values of 0 and 255 are treated outside of the range of values excluding these two values. Link to post Share on other sites More sharing options...
MiDAS Posted March 4, 2019 Share Posted March 4, 2019 WHEN i COME ACROSS THIS SITUATION WITH MY ESU V4'S i FIND ALTERING cv2 TO A HIGHER VALUE SOLVES THE PROBLEM. WHY I DONT KNOW. iT MAY WORK ON THE zIMO Link to post Share on other sites More sharing options...
TheSnapper Posted March 4, 2019 Author Share Posted March 4, 2019 Good point Ray, I'll take a look Tim Link to post Share on other sites More sharing options...
Nigelcliffe Posted March 4, 2019 Share Posted March 4, 2019 I'd be tempted to try different values in CV57, the track reference voltage. It can be used for a variety of tricks, not just its official purpose. It may slow down the loco a bit. But, the chuff rate ought to be related to the BEMF measured motor rotation speed, which means you're up against a limit with the project you have. Are you sure you don't have a four cylinder sound project (ie. twice as many chuffs per wheel revolution than that needed ? ). - Nigel Link to post Share on other sites More sharing options...
TheSnapper Posted March 12, 2019 Author Share Posted March 12, 2019 All Thanks for you suggestions, but nothing has made any difference. The customer will accept the situation & hopefully contemplate a future re-blow! Many thanks Tim Link to post Share on other sites More sharing options...
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