RMweb Premium Ray H Posted December 18, 2020 RMweb Premium Share Posted December 18, 2020 I've just fitted a decoder to a colleague's O gauge DMU that appears to have a motor not too different to the old Tri-ang X04 in design. It certainly uses what look like the old Tri-ang motor brushes. I have managed to set the number that the unit will use but I can't seem to read the values in any of the few CVs that I've tried looking at. The motor seems to run OK and the few sounds that I tried appear to work. Is there something in the older motors that makes it difficult to read their decoder CVs? Link to post Share on other sites More sharing options...
johnb Posted December 18, 2020 Share Posted December 18, 2020 Which decoder are you using? Some have a limited number of adjustable CVs. Link to post Share on other sites More sharing options...
RMweb Premium Ray H Posted December 18, 2020 Author RMweb Premium Share Posted December 18, 2020 1 hour ago, johnb said: Which decoder are you using? Some have a limited number of adjustable CVs. Its a Zimo MX645. I was attempting to set it up using my PowerCab on the programming track. The first thing it usually does is to read the Make then the Version. It responded with 255 for both which I know is incorrect. Likewise it returned all sorts of weird values for CV8 - the Make - and CV29 - which I wanted to change to get the vehicle running the right way round. The weird bit came in the shape of different values each time I tried to read those CVs. As I said, I was able to set up the 4 digit loco address that we want it to carry. I just wondered whether there is something strange about the older motors' current draw that upsets things. The vehicle seems to run quite happily so it isn't to much of a problem. We'll simply make a note of any CVs we change and the values we change them to. Link to post Share on other sites More sharing options...
RMweb Premium Izzy Posted December 18, 2020 RMweb Premium Share Posted December 18, 2020 Whenever I get weird readings on the program track I always assume that there is some fault somewhere. Residual current flowing where it shouldn’t or a poor soldered joint not passing current properly. Repeated wrong readings indicate it’s not an aspect to ignore, MX645’s aren’t cheap are they, although I’m not sure excess current draw would show up like this on the program track. There were quite a few open frame X04 type motors used in O gauge in the past, KTM’s were one such, I’ve still got a couple somewhere. But they probably have fairly hefty current consumption compared to today’s more normal can types. Izzy Link to post Share on other sites More sharing options...
RMweb Premium Izzy Posted December 19, 2020 RMweb Premium Share Posted December 19, 2020 I don't know if this will be of any help, it might to someone, but here is a shot of two different sized KTM motors alongside a Mashima 1833. I dug them all out of their hidey-hole. It seems they draw roughly the same level of current running and at stall as the Mashima. 350ma running light, 650ma completely stalled, so well within the MX645 capabilities of 1.2amp average and 2.5amp max peak. Izzy Link to post Share on other sites More sharing options...
RMweb Premium Ray H Posted December 19, 2020 Author RMweb Premium Share Posted December 19, 2020 The motor itself (in solation and removed from the vehicle/bogie ran happily with a PP3 (9v) battery across the brushes. Link to post Share on other sites More sharing options...
RAF96 Posted December 19, 2020 Share Posted December 19, 2020 Some decoders do not support read-back, nor do those controllers that effectively program on the main. Link to post Share on other sites More sharing options...
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