JWRStation Posted August 17, 2020 Share Posted August 17, 2020 OK, might be covered before but I cannot find it...!!!I attempted to fit a DCC decoder to an old R374 Battle of Britain class which has the old X03 type motors. Fully serviced and has excellent slow speed response and will creep along with the motor barely turning. Very low Amps needed to move off however, stall test gave 900 mA which means Hornby DCC decoders way under spec so I upped the Spec to Hattons DCR which has 1.6 A max and continious rating of 1.1 A.Fitted, checked and put on the main DCC track, forward movement requested followed by a flick of the motor and a big puff of smoke from the decoder....Tested again on the Analogue track and even with full output on the speed dial; only 900 mA.Loath to destroy another decoder so before doing anything else, has anyone been succesful in fitting a decoder to the older motors???? Link to comment Share on other sites More sharing options...
96RAF Posted August 17, 2020 Share Posted August 17, 2020 Margate-Richmond did a concersion guide.You will have to copy and paste into your browser as the live link facility is still broken.https://www.hornby.com/uk-en/forum/making-the-x03-and-x04-dcc-fitted-the-proper-way!/?p=1 This is also useful...https://www.airfix.com/uk-en/forum/post/view/topic_id/24262/?p=4 Link to comment Share on other sites More sharing options...
JWRStation Posted August 17, 2020 Author Share Posted August 17, 2020 Thanks and got it.....Had not done the best job of fitting as it was a temporay 'test' to prove things; ended up with a short between a decoder motor wire and feed wire.. OWN GOAL and as the well known moto goes. "If its worth doing then do it properly".Fortunately not TOO expensive a relearn of an old lesson and at least TWO layer of heat shrink onto the next fitting of the spring tension wire... Link to comment Share on other sites More sharing options...
ColinB Posted August 17, 2020 Share Posted August 17, 2020 The issue is as I found when converting my ringfield motors, is that the maximum ratings for some of the these DCC decoders are not real life values. On a couple of they the loco stalled at a point because of an issue with the wheels and the decoder fried. The specifications for these decoders ! assume take no account of being squashed up inside a loco body where there is very little cooling. Zimo make a 2 amp version which when I talked to YouChoos said that it should be good for 2 amps. As some consolation when converting my old locos, I blew up Hornby, DCC Concepts and Hattons decoders with obvious over current, although their specifications said I was well within them. The Hattons one was specified at 1.6 amps max, but it fried when my Ringfield based loco stalled at a point. Link to comment Share on other sites More sharing options...
JWRStation Posted August 17, 2020 Author Share Posted August 17, 2020 Interesting.I have now tested a couple of Lima Ringfield motors which resulted in a stall test of 600mA ish for both.Trick seems to be to ensure adequate cooling with removal of the heat shrink covering, which is quite thick, and locating in the body with clearance all around... I have found that most of the older motored models do seem to have lots of body clearance... Link to comment Share on other sites More sharing options...
JWRStation Posted August 17, 2020 Author Share Posted August 17, 2020 As an aside, I have a selection of fast blow fuses now on the way so a bit of experimentation on decoder protection...15p for a fuse or £15 for a decoder........!!!!!!!!!!!!!!!! Link to comment Share on other sites More sharing options...
ColinB Posted August 17, 2020 Share Posted August 17, 2020 Yes, you will find a post of mine about fitting a resetable fuse. I bought them but I never got round to it, I think I just bought better decoders. I got roughly the same values for my Hornby ringfields, which is why I could not understand how a Hattons 1.6 amp one could die. I replaced it with a Zimo standard £20.00 one and have had no issues since. Since then I have used Zimo for all my DCC decoders, at £20.00 they are £4.00 dearer than the Hornby on discount, but they seem to be a lot harder to break. Link to comment Share on other sites More sharing options...
Flashbang Posted August 17, 2020 Share Posted August 17, 2020 Unfortunately fuses, regardless of whether fast blow or standard rated rupturing, will be far to slow to protect any decoder or a DCC system.Equally any self resetting circuit breaker will not trip fast enough and they will allow too much current to flow before tripping. This is way DCC systems use all electronic means of tripping the power.Fuses or Thermal Circuit Breakers are often used on DC (Analogue) systems. Link to comment Share on other sites More sharing options...
JWRStation Posted August 18, 2020 Author Share Posted August 18, 2020 Actually I was thinking of PTC's. Zimo have overload protection which automatically resets which is the way PTC's work so one of these in the motor line? Say 500mA which most of the models 'normally' stay below However, when stalled may go 600 mA upwards which the PTC should then up its internal resistance and hold it down to just above 500 even if the stall curent would be 900 mA for an X03.. Link to comment Share on other sites More sharing options...
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