DMU/EMU lighting

[AndrewP]

I've had an odd problem; I've a n gauge class 101 which takes two decoders - one for the dummy unit's lights. I plugged them in and, following internet suggestions, set them both to the same ID with RM, but the lights only worked in one unit - I swapped the decoders between the cars and the working lights moved with the decoders, so I thought I had a faulty decoder. However, I tried changing the ID of one decoder and voila, both sets of lights started working. I've set the motorised and dummy cars to be a "double header" and everything works, but I can't understand why setting the same ID didn't work.

[AndrewP]

Sorry; this somehow got posted into general DCC rather than Railmaster.

[Fishmanoz]

Strange Andrew, shouldn't happen.  What happens if you put the power car on the same address as you now have in the dummy car?  Or put another way, don't use the ID you used originally when you had the problem, set both to a different one.

[RDS]

Sorry; this somehow got posted into general DCC rather than Railmaster.

I think it is correctly placed in the DCC section.

There have been some instances of decoders needing a motor load (not just lights) when they are programmed but if it works on a different id it seems to rule that out.

[AndrewP]

Thanks for the suggestion; I did try putting each decoder in the powered car and setting the ID to 101 for both and the lights only worked with one decoder, I changed the id code in the one that didn't work to 102 and it started working. At the moment, I have the motorised decoder set to ID 101 and the dummy to 102 and the lights work in both; if I set the two as a double header, then everything works - forward/back lights switch correctly. I changed the motorised to 102 and the lights stopped working - although I could control it from RM. I tried a different loco and decoder with working lights, changed the ID to 101 and the lights stopped working, switched it back to 47 and the lights work again. Perhaps there's something funny about the ID 101.

[AndrewP]

Resolved! I bought a Dapol class 86 and it's lights didn't work at all; I did some hunting through the past problems on the net and the problem is CV29 can get corrupted when changing Bachmann decoders; to fix the problem, I set CV8 to 8 - to reset the decoder, then read CV29 - it came back as 6. Then changed the ID to 101 and explicitely set CV29 to 6 and voila, the lights work and display forward/reverse correctly.

[Michael_A]

Annoys me that you even need two decoders, especially when all the second one does is control lights. Solution is a wired coupling, similar to what Bmann have done with their later DMU's and the Blue Pullman (that needs two because it has two motors, fair enough)

 

What happens if you don't fit the second decoder? Do the lights just stay on permanently with DCC?

[AndrewP]

Yes, it was a unexpected expense I hunted around to get a Bachmann decoder for £14; if you don't have the dummy decoder plugged in, no lights will come on - I suspect if you leave the dummy in, all the lights (forward and reverse) will come on; I haven't tried that.