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Won't run in DCC

Started by hywel43, February 24, 2013, 09:29:46 AM

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hywel43

I have two new Bachmann n scale locos (with dual mode decoders) that won't run in straight DC. The first is an RS3. The light comes on but the loco does not move at any voltage. The 2nd is a 44 tonner that will not run at low speeds but will jump to life at maybe 50 scale miles per hour when you really crank the throttle up and give it a little shove. I have a MRC Tech II power pack with the momentum turned off. Kind of sucks that these "dual mode" decoders won't work as they should. I have no access to a DCC system so what do I do?

Added: I have another Bachmann RS3 with the dual mode decoder that runs perfectly with good low-speed performance. I tried them all with an old Revell power pack with pretty much the same results. I know that the dual mode decoder will require more throttle input than a DC loco but that 44 tonner starts jerking ahead until a high enough voltage is reached and then it sprints down the track at the moment the right voltage is reached. It's almost like the decoder is giving quick shots of voltage because the light flickers on and off when it is jumping and then goes steady when it takes off at warp speed.  I'm wondering how hard it would be to eliminate the decoder completely and make these straight DC locos for now. Would I lose the nice bright lights?

mf5117

There is a difference in a dual mode decoder (one with a switch)
and a plain decoder. Both will work in DCC and DC. A dual mode
decoder, like the one Atlas uses, will work like any other DCC
engine when in DCC mode, and like any other alalog engine when
in analog mode. A standard DCC decoder will work well like
any other DCC equipped loco when used on a DCC system, but will
not run as well on DC.  you can run it but no, you won't
like the performance enough to want to use it.

With no sound decoders, it will probably take quite a bit of turning with the control knob before the loco starts to move so do not be surprised.

Also, make sure the DC controller does not have pulse power on as some decoders only want pure DC.
The decoders send pulse power to the motor but has to overcome the mechanical resistance of the loco motor and gears before the loco can move.