SD-45 DCC ready - conversion to DCC

[trainman75]

The SD-45 (DCC ready) was tested on DC and everything worked fine: motor, direction and lights.

I then installed a NCE D13SRP decoder in the engine.  After removing the jumper board, the decoder's NMRA plug was installed per the marking on the engine's circuit board.  The following was observed: the engine ran but it's direction of travel was long-hood forward (reverse of what it should be) and neither LED would light.  I reversed the NMRA connector and the engine ran properly (short-hood forward) but again neither LED would light.  The decoder was removed and the jumper board was reinstalled and again everything functioned normally.

From reading other literature, it seems this engine has capacitors and inductors that are used to prevent radio noise when operated on DC power, and these are required to be removed for proper DCC operation.   There are 2 inductors (L1 & L2) and 4 capacitors (C1, C3, C4 & C5).

L1, L2, C4 & C5 appear to be in the motor circuit and C1 & C3 may be related to the LED's circuitry.

Questions:
Are all components listed above to be removed?  If not, which ones?
Are any additionl component changes required to get the LED's to work properly?

[RAM]

Try turning the plug around.

[Yampa Bob]

I have had similar experiences installing non-Bachmann decoders in Bachmann "DCC ready" locomotives. In a few instances, the locos wouldn't work with any decoder, including Bachmann's.  My only solution was to remove the board and hard wire the decoder. 

Apparently Bachmann decoders have circuitry that is compatible with the suppression components on the board, some other brands do not. This non-compatibility issue is one that needs to be seriously addressed by the manufacturer, i.e. Kader/Bachmann industries ETAL.

[Hunt]

...
Bachmann decoders have circuitry that is compatible with the suppression components on the board, some other brands do not. This non-compatibility issue is one that needs to be seriously addressed by the factory.
...

Not a Bachmann factory issue to address.

[Hunt]

If your Decoder NCE D13SRP is version 3.5
Then
Try first using Function F0 as it should turns lights on and off.

Then if needed
Front light bright in forward, dim in reverse. Set CV120 to 44
Reverse light bright in reverse, dim in forward. Set CV121 to 40
You may find you need to reverse these settings.

This is covered in the decoder's documentation.



If F0 does not turn lights on/off ....  I am wondering if the NMRA 8-pin socket in your locomotive is correctly wired or is damaged or if the output of the decoder is damaged.



Cut one leg of (or remove) the capacitors across the motor circuit.

To remove or not remove capacitors across the motor circuit is an issue about poor motor speed control. Lights have not been part of the issue to date.

Some decoders have an internal capacitor to do the suppression and the decoder is tuned to work with it.  The external capacitors on the Bachmann PCB interferes, resulting in poor motor speed control/performance.

[pdlethbridge]

I agree with Bob, Hunt your wrong. There have been issues with capacitors for years. Bachmann should fix the problem. Other manufacturers have not had that issue or have addressed the issue. Why don't you check out Jim Banners site for installing a decoder in a 2-8-0. Or is Jim wrong?

[Hunt]

pdlethbridge,
Notice Yampa Bob edited the wording of his post (January 14, 2009, 01:01:10 AM).

As I recall, some of Jim's 2-8-0 documentation is out of date in that some of the questions he raises have be addressed by Bachmann. As to the capacitors on the PCB, his documentation does not materially differ with anything I have ever written on this Board on the subject.



Yampa Bob,
It remains to be seen what, if anything else, Kader does about RF suppression circuits. After all as you noted, Bachmann decoders are compatible with the RF suppression circuitry used in Bachmann locomotives.

See http://www.nmra.com/standards/DCC/WGpublic/discussion_topics.html#Topic0709211
Perhaps the work by the NMRA will help in time and make RF suppression less of an issue to the modeler.

[pdlethbridge]

RF suppression seems to be a European problem, not a US problem. It seems that decoders of other makers should work without modifying the boards in Bachmann locos. Digitrax, NCE and TCS all show that removal of the caps is necessary for good operation.

[trainman75]

Thanks to everyone for their inputs.  Very enlightening!

As to my original issues, I intend to discard the printed circuit board and install the decoder per the standard decoder installation requirements.  This is easier than trying to decipher the circuit board, and also allows more flexibility in the mounting of the decoder.

Happy railroading!