Model Railroading > Athearn SD70 ACE decoder question

I have the paint and decals part of modeling down, but I haven't played around much with the lighting and other electonical things.    I have an HO SD70ACE and bought a DH165AO Digitrax decoder to go in it.   It will have no sound, but two replacement 1.5 volt 15mA bulbs in the rear, and 4 LED's in the headlights and ditch lights which are SMD Warm White Prewired 12v that have a resistor built in (from hdamodelworx.com).  My question, is this decoder ok for this loco, and will this decoder be easy to program once I get it on DCC?

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The decoder you have there will require you to completely strip the PC board out of the model and hard wire your new decoder in.  It looks like you have an 8 pin plug in option, plus the athearn plug.  I would suggest getting a decoder that plugs into the PC board instead.   If you do install the one shown, make sure the output is 1.5 volts or you will instantly burn up your light bulbs.  P.S., changing those bulbs isn't going to be fun either!   As far as programming, I have an NCE system so programming is extremely easy, regardless of who made the decoder.  

Good Luck!

~Dave
 

The model motherboard has the option of an 8 pin or 9 pin plug in decoder. By using these options you get to take advantage of the 1.5v lighting circuits on the motherboard. This will save you adding resistors from the drop in decoder you have.

An easier install for this locomotive would be to remove the dummy plug attached to the 9 pin harness and plug in a digitrax DH166 plug in decoder with no harness attached. NCE and TCS have equivalent 9 pin plug in decoders to go with your preference.

To use the front light leds with the hdamodelworx device you will have to tap into the blue wire coming out of the 9 pin socket. That wire needs to continue to the motherboard to make the rear 1.5v headlight work. The tap goes to the + side of your LED device. The negative wire from the device goes to the front headlight connection. The front + connection on the motherboard will be left open since the higher voltage comes from the power device.


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Edited 2 time(s). Last edit at 06/30/15 18:53 by fbe.

Completely disagree.  My experience with using the Athearn factory boards with a decoder plugged in is that they're fine as long as you stick with 1.5V lamps.  As soon as you want to go to LED, the Athearn board becomes a PITA trying to figure out where to attach the LEDs so that they get 12V (or 14V).  Athearn has done several generations of these things and they're not all the same.  The decoder shown should be perfect for this application and it's a simple matter of removing the Athearn board and reconnecting the wires to the appropriate locations on the decoder.

Nathan Beauheim
Cheyenne, WY

If you take off the 4 diodes on each end of the athearn board,you will have 12 volts to use. the diodes limit the voltage to 1.5 volt. Have done this on numerous loco that I wanted to use leds and it worked fine. That way you can use the tabs on the end of the board


Mike



Edited 1 time(s). Last edit at 07/02/15 08:57 by bnsf70mac.