# Need wiring help with decoder



## nrscroller (Dec 3, 2018)

Hi
I just got my digitrax DH126D decoder in the mail. I got motor and trucks wired ok but now no lights. I am doing a older broadway limited SW7 and it has 2 light wires on both ends. I put one wire on each end to white and yellow and the other wires to the common blue on the decoder as it says.
Thanks Bill


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## Tom_C (Jan 8, 2016)

Dumb question, but did you turn the lights on with the controller?

Also, if they're LEDs they need to be connected correctly.


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## wvgca (Jan 21, 2013)

yes, if they are leds , it makes a difference where the blue goes [and the others], and you =may= also need a resistor to drop the current


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## DonR (Oct 18, 2012)

The BLUE wire on decoders is the common, and
it is POSITIVE. So, if you are using LEDs you'll
need to see that the blue wire connects to the
positive wire on each LED.

Decoder light feed is 12 V DC. If you use LEDs you must
provide a resistor to match. 


Don


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## Andreash (Dec 30, 2018)

If they are incandescent bulbs, they will burn out when turned on with no resisters. It’s a good practice to switch to leds anyways, as you are installing a decoder anyways ( tools, disassembly, etc). Using Evans designs leds is fool proof. + and - don’t matter, and can be hooked up to white/or yellow, and to common easily..cheers


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## J.Albert1949 (Feb 3, 2018)

I balked at the idea of using LEDs at first on some of my engines. I didn't want to fool with trying to solder resistors to the LED leads and such.

I found there are a few sellers on ebay who will sell headlight-compatible LEDs with the resistor (and heat-shrink tape) pre-configured. Just "put these in and go".

_A proviso:_
The size of these LEDs will limit their usage to "headlights only". Also, they may be a bit too large for some of the "slots" into which headlights fit in existing frames/weights.


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## Andreash (Dec 30, 2018)

Evans Design Leds come in pico, and nano sizes. Incredibly small, and some come with 4 leds all connected together. I’ve used that configuration,and removed a led that wasn’t required. ( used in a engine that had a nose and high headlight). The 3 mm is a good size for HO, 1.8 is a good secondary choice. The pico would be good for N scale, but space could be issue for resister/polarity control. Check out there website. The fact that they have police light kits for HO is proof to their size working in many train scales..cheers


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