petertg Posted May 25, 2014 Share Posted May 25, 2014 As mentioned in my blog, I have now acquired a new controller allowing me to read and write CVs. I have carried out a few checks on locomotives to familiarize myself with the system. However, there is a situation that I have not cleared up from the instrument instructions, namely: I have two units, a Bachmann Class 108 DMU and an Electrotren push-pull with an electric locomotive at one end and a non-powered driver coach at the other end, which have two decoders each. The two Bachmann decoders and the Electrotren driver coach decoder were fitted by the local shop and I am unaware of the make, although I believe they are Lenz. The locomotive has a Hornby decoder. The problem is that the lights on the Electrotren driver coach have ceased to work. So, I tried to read the decoder to see if it was faulty. The reading I get is “no loco”. Since the lights on the Bachmann trailer coach do work, I tried to read its decoder and got an “error” reading. Since I assume that both vehicles have only function decoders, what do I have to do to read them? I have just read in “Bromsgrove” texts that it might be necessary to place a load on the programming track and then program the function decoder first but how do I know that I am programming the function decoder, or am I programming both decoders simultaneously and then have to reprogram the other decoder? And how do I know that i have correctly programmed the function decoder? Link to post Share on other sites More sharing options...
RhBBob Posted May 25, 2014 Share Posted May 25, 2014 Hi ! I am not sure if a 'function only' decoder has the spare pins for a motor, but if so, please read on:- I had this problem and even using the Sprog 2 programmer - http://www.sprog-dcc.co.uk/ - I could not access the decoder in a driving trailer coach. So I wired in a spare electric motor and the programmer immediately recognised the decoder ! I guess that the presence of a motor is the deciding factor but I cannot tell you why !! Link to post Share on other sites More sharing options...
Nigelcliffe Posted May 25, 2014 Share Posted May 25, 2014 The usual requirement to generate a programming "acknowledgement" pulse is enough current flowing in a decoder. A motor connected to any output usually does this, or a light bulb. But an LED uses far too little current, so there isn't enough flowing in the decoder to get the pulse. Link to post Share on other sites More sharing options...
petertg Posted May 27, 2014 Author Share Posted May 27, 2014 Thanks for the information received. I have not yet tried again with a locomotive also on the track because I have been occupied with other things and also replacing a defective turnout. Link to post Share on other sites More sharing options...
Crosland Posted May 28, 2014 Share Posted May 28, 2014 The problem is that the lights on the Electrotren driver coach have ceased to work. So, I tried to read the decoder to see if it I have just read in “Bromsgrove” texts that it might be necessary to place a load on the programming track and then program the function decoder first but how do I know that I am programming the function decoder, or am I programming both decoders simultaneously and then have to reprogram the other decoder? And how do I know that i have correctly programmed the function decoder? You will write both decoders if you put another loco on the track. You have no way of knowing that the function decoder is programmed correctly, other than testing it. Reading is still a problem. Andrew Link to post Share on other sites More sharing options...
RMweb Premium Steven B Posted May 28, 2014 RMweb Premium Share Posted May 28, 2014 Are you 100% sure that the non-motorised half of the unit has a function only decoder? It's more likely they've got a standard decoder. It's easy enough to check - remove the decoder from the dummy vehicle and put it in the powered one. Happy modelling. Steven B. Link to post Share on other sites More sharing options...
Sunnysa Posted May 29, 2014 Share Posted May 29, 2014 Swapping decoders from loco to loco to test is silly and extra time wasting. The secret is, get a decoder tester. Believe me it saves a lot of time and frustration. Decoder tester is easy and cheap to make or any hobby shop worth their salt will have them or can get them at reasonable cost. Generally, a chip tester is approx the cost of a good decoder. Mine is 17yrs old and would not be without it. Cheers Ian Link to post Share on other sites More sharing options...
petertg Posted May 29, 2014 Author Share Posted May 29, 2014 Thanks for the comments. However, I can't swap the decoder to a locomotive because it's hardwired in. I'll take it into the shop that fitted the decoder and see what he can do for me. Link to post Share on other sites More sharing options...
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