DD40AX digital control

[Arnhegen]

Hello,

I am a Dutch N-gauge user who bought a very nice Bachmann DD40AX Centennial locomotive with DCC build in during a visit to the US last week.

No I am home and of course put the loc on my track right away (I am using Fleischmann track in combination with an Intellibox for digital control) and the loc shows good, smooth movement under analog control but moves around shaky and which looks like varying speed under digital control and as far as I can see the decoder is programmed properly (although this type of decoder is unknown to me)

Is this something that has been experienced by others and if so is there a solution ?

I would appreciate your suggestions

Regards

Ronald

[C855B]

I've run three different "copies" of the new DDA40X under DCC, and aside from unusually long momentum settings have had no problem as you describe.

That said, this decoder is very basic - too basic - and is the process of being replaced in all of mine.

[Arnhegen]

Ok thanks

With what type of decoder you think of replacing them?

By the way in digital operation when starting the loc to drive there is a sort of humming sound which is not the case in analog operation, where is runs smooth. Any suggestions?

[C855B]

I'm replacing them with a TCS (Train Control Systems) M4. I'm rewiring mine for separate control of the beacon and future provision for controlling the marker lights separately. If I was replacing the stock decoder pin-for-pin, it would be with the TCS M1.

The humming you hear is likely a power dithering mode to help with low-speed control. It's normal with low-end decoder designs.

[Arnhegen]

Thanks for the advice and suggestions.

[bobrandell]

I am wondering why you are considering the TCS M1 specifically or is this your standard decoder? My DD40AX (new version) runs acceptably with the supplied decoder, unfortunately my Zephyr cannot see the engine and so I am stuck with it on address 03. I have about 3 of the original DD40's with the split gears out of which we produced one functioning unit using F-unit gears. When I replace the decoder in the new DD40 I would like to find a sound decoder that would fit. QSI has the appropriate sound files, ie. 2X16 cylinder prime movers and the correct horn but their sound files are specific to their decoders and none of theirs fits. Does anyone know which sound decoder Bachmann had in mind when they called this loco sound ready?

[jprince46]

Put a 1k resistor across the programming track.  That should allow you to program the decoder and set the address.

This is a common problem with Zephyrs and several manufacturers decoders.

[jwoj69]

I'm using myh DD40ax with MRC Prodigy. No problems and no need to reprogram or replace decoder.
jack

[davidone]

I use the power cab and had no problems programming in the ops mode. Also take the shell off and tighten the 3 screws of the frame halves. Really makes a difference on how the DD runs.

Dave

[herc driver]

If you don't have a 1k resistor, just add enough length to your programming track and place a lighted passenger car on the rails with the DD unit (which is what I did on my Zephyr system).  Your Zephyr  system should be able to "see" the decoder and program a new address.