Dcc mystery, please help.....

[jward]

my friend and i have run into a problem with several of our dcc locomotives running on dc but not dcc.

these locomotives won't respond to a factory default reset, on his nce system. they have a variety of decoders in them, my 2 are bachmann gp40s, his have digitrax (dh121) or nce decoders. all locomotives were last run in consists with other locomotives.

my 2 locomotives have the original factory installed secoders, the others mostly have decoders removed from other locomotives and transplanted into their current homes.

we have been unable to do any programming whatsoever on these locomotives.

is there a way to reset them, or to remove them from their programmed consists, without actually knowing what address they were consisted under? is there a way to lookup the consist number they are programmed to?

any help would be appreciated.....

[OldTimer]

There are three types of consisting:  Basic, which simply assigns the same address to each unit; Universal, in which the command station keeps track of the MU info, and Advanced, in which the consisting information is stored in the decoder.

My guess is that you set up an advanced consist and then did not break it apart...so the decoders still think they're mu-d.  CV 19 holds the advanced consist address.  Try setting CV 19 to 0 (zero) to disable advanced consisting addressing.

Hope this helps.

[jward]

we tried resetting cv19 to 0. this brought back all locomotives except my two gp40s. reading back cv19 on these 2 shows that cv19 has been reset to 0 as well, but they still won't respond to reprogramming. when we try to reprogram them, they lurch like the the decoder is accepting the new address, but we cannot get them to run on dcc. they work fine on dc though.

[OldTimer]

Now that you've reset cv19 manually, try resetting the decoder to factory defaults and see if it will then let you set its address.  I'd try a two digit address for starters.

[Jim Banner]

Are we talking about Bachmann decoders here?  Or could they be decoders with decoder lock?  Can you read back CV's 1, 17, 18 and 29?  Then we can at least figure out what addresses they are presently programmed to.

Jim

[jward]

i won't be able to checque on these further until next weekend, but i believe we were able to read back the long address on cv 17 & 18. cv19 was definitely 0. not sure about cv1.

and yes, these are the bachman decoders that came in these locomotives.

[Jim Banner]

That fourth CV I was wondering about was CV29.  It will tell you whether the decoder is set for short (CV1) address or long (CV17 and CV18) address.  Do you know how to calculate the long address from the contents of CV's 17 and 18?  Particularly the part about the hexC000 offset?

Jim