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Model Railroading > DCC problem with older Bachmann 2-8-0


Date: 11/09/10 16:34
DCC problem with older Bachmann 2-8-0
Author: slagg

I'm helping a friend install a decoder in an older Bachmann Spectrum 2-8-0 (possibly first run?). The tender is equipped with an 8-pin socket, and an NCE D14SR fits nicely. However, the locomotive behaves oddly. At first it wouldn't run at all, but we got it to work by reversing the orientation of the decoder and setting the config bit to reverse the direction of travel of the locomotive. This worked for a while, then we started having problems where the engine would not stop, even at speed step 0. Sometimes it will always run in one direction i.e. forward when you've selected forward and forward when you've selected reverse. Also, if the headlight is turned on it stays on whether the engine is running forward or backward.

Another friend vaguely remembered something about a problem with the way the DCC socket was wired with these early Bachmann engines and thought that there might be a diode on the locomotive's circuit board that needs to be removed. I've searched several forums and can't find anything on this problem, probably because the engine is so old that the relevant postings have been archived or deleted. Can anybody help?

Thanks,
Joel Slagg



Date: 11/09/10 19:16
Re: DCC problem with older Bachmann 2-8-0
Author: wc581

I had a customer that had an issue with these locos, ran fine on NCE & Digitrax, however on Atlas DCC system had no slow speed control. I tried different DCC decoder manufacture decoders. what I had to do was swap the board in the tenders with a later model board, or remove the board and hard-wire and all of your problems will go away

Mike Slater



Date: 11/10/10 00:07
Re: DCC problem with older Bachmann 2-8-0
Author: markloos

There was a known problem with the early Bachmann steam locos. There is a capacitor and 2 coils on the PCB, that form a filter that act to cut down interference from the motor brushes. This causes erratic behavior with DCC. The fix was to cut one lead of the capacitor thereby removing to filter. This may be your problem - give it a try.

Mark
www.loostrains.com




Date: 11/10/10 09:39
Re: DCC problem with older Bachmann 2-8-0
Author: WP282

markloos Wrote:
-------------------------------------------------------
> There was a known problem with the early Bachmann
> steam locos. There is a capacitor and 2 coils on
> the PCB, that form a filter that act to cut down
> interference from the motor brushes. This causes
> erratic behavior with DCC. The fix was to cut one
> lead of the capacitor thereby removing to filter.
> This may be your problem - give it a try.
>
> Mark
> www.loostrains.com

Pardon my ignorance, but in the referenced photo, which one is the capacitor?



Date: 11/10/10 10:46
Re: DCC problem with older Bachmann 2-8-0
Author: imrl

It's the orange one with the cut lead.



Date: 11/11/10 12:31
Re: DCC problem with older Bachmann 2-8-0
Author: slagg

Cutting the capacitor lead did fix the problem. The engine runs fine, now. Thanks for the suggestion, Mark.

Joel Slagg



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