Model Railroading > HO DCC Decoder install question.

Question for the masses. I recently installed an old NCE DA102 decoder in a newer Bachmann GP38-2. It is to be a runner on our club layout. One issues I have is that the headlights are on opposite the direction of travel for the locomotive. I can not see anything in the instructions for the decoder to remap the lights. Will reversing the motor leads to the decoder solve the problem or do I have to rewire the lights?  Thanks for your help.

Jim

James Bartelt
Port Washington, WI
Metro Model Railroad Club, Ltd

I just had that problem with a NCE DA-SR. I used decoder pro with my laptop and Digitrax PR3 and told the front light to light in reverse and the rear light to light when going forward. I am sure there is a CV for that but decoder pro works so easily and painlessly that is what I use. If you do not have decoder pro you might want to check with NCE's website to see what CV's to use to change the lights.

Scott O'Dell

If the yellow wire goes to the front light and the white wire goes to the rear the headlights are wired wrong.

If the loco moves forward when other locos move forward the motor is wired OK, if it moves against the flow of the rest of the fleet and the wires need to be swapped.

You could always try the wire swap for the motor and see what happens if it does not do anything what have you lost. It probably would change the direction of travel. 

Scott O'Dell

fbe:
This does not help as the decoder does not have wires but solder tabs for the connections. Picture for reference.

Jim

James Bartelt
Port Washington, WI
Metro Model Railroad Club, Ltd



Edited 1 time(s). Last edit at 03/21/19 19:47 by scrimjimmy.

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So the photo is upside down but mostly things are labeled. Let's begin by looking at the decoder like it is installed on top of the motor. Note there are the words rear and front along the top edge of the decoder. Make sure the loco is oriented to match the decoder.

Looking down the length of the decoder rear to front the right outside terminals get the red track wires. The left outside terminals get the black track wires. If they are all black sort them out and place the wire from the truck to the terminal directly above it.

Between the outside terminals on the front end there is one labeled C for the + common blue light wire. Number 1 is for the white front headlight wire.

The rear end is the same the red track wire and black wire will gobto the same side as the wires on the front. C connects to the blue light common and 2 is for the yellow rear headlight wire.

On both ends you see rectangular resistors inside the end terminals. Note there is a track which connects the end of the resistor. Electricity takes the path of least resistance effectively bypassing the resistor making light output at track voltage in the 12v-16v range. Say you want to use led headlights, you do not need to add a resistor, it is already there! Follow the 1 and 2 terminals until the circuit trace reaches the small resistor. Use a sharp scribe and scratch all the way through the circuit trace which bypasses the resistor. Now the light power needs to go through the resistor reducing the voltage to 3v for the led. The connections for light functions 3, 4 and 5 are on the front end each with the appropriate number and a C. You can use the individual c terminal hole or the end terminal C. Note all the auxiliary functions have their own bypassed surface mount resistor for leds.

On the edge of the decoder in the middle the + is for the orange motor and grey goes for the - motor wire.

Please let us know how this works out for you. NCE has a downloadable instruction sheet for their DA-SR decoders.



Edited 1 time(s). Last edit at 03/21/19 20:33 by fbe.

list of retired decoders, D102 is ninth down,https://ncedcc.zendesk.com/hc/en-us/articles/201756029-Retired-Decoder-Manuals

Ed Stewart
Jacksonville, FL

How did the install go?