4-4-0 decoder instal with sound

[csgmtu]

Hello group,
I have installed the MRD 1665 steam sound only decoder and I am happy with the sound (cannot beat $37.00).
I am having trouble fitting everything in the tender. I have a digitrax decoder that i would like to use instead of the Bachmann decoder. has anyone tried replacing the factor installed DC/DCC decoder and replaced it with a DCC only decoder?

basically I am asking what should I remove.

thanks

cg

[JohnR]

I've replaced several Bachmann decoders with Digitrax DZ series decoders.  I just swapped them (ie. no changes to the circuit board.

-John

[Tomcat]

I´ve changed a lot of Bachmann decoders for Tsunamis and ESU Loksound decoders too.
You can even use the plug of the Bachmann decoder for the new installation. If you cut off the plug and solder the cords, colour by colour to the new decoder, you´re fine. The Bachmann decoders won´t make a big deal on EBAY, so you can re-use the plug and wiring. Use the smallest shrink tubing you can get to isolate the soldering spots from each other and this is a straightforward job...

Cheers, Tom

[Jim Banner]

Yes, you can install a motion only decoder to complement your sound only decoder.  You may even install a small motion decoder like the Digitrax DZ125 right in the locomotive to reduce the number of wires between the locomotive and the tender and save space in the tender.  Just remove everything from the tender except the pickup wires and wire the motion decoder as if the adapter board had never existed.  In addition to the two pickup wires connected to the wheels, you need only one more wire between locomotive and tender and you only need it if you use a tender light.  Connect the other side of the tender light to the cathode ends (the ends with the stripes) of two diodes, then connect the opposite ends of the diodes, one to each pickup wire.  1N4001 diodes are a good choice.  This trick with two diodes replaces the blue wire connection to the tender light and takes up very little space.  The rest of the space inside the tender is then available for the decoder, speaker and baffle.

The DZ125 decoder is rated for 1 amp.  I recommend that you measure the stall current of the locomotive's motor at 12 volts dc to make sure it is does not draw more than 1 amp (it should not.)  The DZ125 can be programmed to automatically switch to dc but I do not know how your MRC decoder handles dc.  The DZ125 also has BEMF control which is a very nice feature with steam locomotives.  When turned on, it allows you to reliably start right at the beginning of the throttle and gives smooth control at low speeds.  No worries about the locomotive chuffing away but not moving or having to get some speed on before the chuffing starts.  I am assuming that you have a DCC system capable of programing the necessary CV's or can have someone program them for you.  They need to be programmed only once, except the address which you can change any time you want.

Jim 

[pjf]

Hello cg, I just purchased  a 4-4-0 and would like to buy and install the MRC 1665.
I would like to find out if it will work with the "EZ Command" controller. I don't have the ability to reprogram so the factory setting would have to do. Thanks