I have a rather bizarre situation that I’m hoping someone can help shed some light on.
I installed a Digitrax DH163L0 into an HO Proto 2000 GP38-2. The front and rear incandescent headlights that came the locomotive worked fine. However, I prefer 3mm LED headlights so I swapped them out.
According to the DH163L0 manual, F0f and F0r have an output of 1.5V. So the LEDs should work without the need to add a resistor. The problem that I’m running into is that the LEDs won’t light up.
Here’s what I’ve done so far:
Double, triple, and quadruple-checked several times over to make sure that the wires are attached to the correct lead of the LED and the correct tab of the NMRA plug:
The issue is that the P2K GP38-2s and SD60Ms have number board lights wired strangely. They don’t work as a drop in with the L0 decoders. See the Digitrax application note.
This is only a problem on P2Ks with number board lights. Otherwise the L0 decoder is a drop in replacement on other P2K models. The net of this is to wire the number board lamp to a function output and then leave the front/back lights wired as is to the decoder. To test it just pull one of the number board lamp leads off and leave it hanging. Things should start to operate fine. Then just pick with function output to use for it and wire it up.
Jeff, I am already aware of the number board issues with the P2K GP38-2 from Tony’s Train Exchange web site. I rewired (corrected the problems) with the NMRA plug. I guess I should go and double-check that again. I’ll also look at the Digitrax blurbs on them. The tests above have been done with the number board lights removed.
You have the LEDs wired backwards – the blue wire is the positive output of a decoder and should go to the long LED lead; the white wire is the negative decoder lead and should go to the short LED lead. If you have more than one LED to power, blue leads should go to every one. The white, yellow, green, etc. decoder wires are the “switched” leads that actually turn the function outputs on and off.
Yes, if you rewired the plug I’d check that. I haven’t had to do that with my P2Ks. All I’ve done is pull off the number board light lead and wire it to an function output. I have the same unit still in the box, if you need me to look at the original wiring or even take a picture of it.
You guys were right. I had the LED wired backwards. It’s been a year or so since I’ve done a decoder install and I had it in my mind that white went to “+” and blue to “-”. [D)] As soon as I switched one for the other, the LEDs lit right up.
Great news. What LEDs are you using ? Maybe you can post a picture. I haven’t gotten around to swapping out locomotive lamps yet with LEDs. Now I have to figure out what is wrong with my new BLI Blueline that won’t take proper extended addressing …
The two that I’m using are 3mm golden-whites from Litchfield Station. I don’t know what particular brand they are. I also have some Miniatronic 3mm golden-whites, which I haven’t used yet. I’ve found that the Miniatronics are usually not quite as “yellow” as the ones from Litchfield station.
Yea, go with LEDs for headlights. They are fantastic and put out a nice, bright, directional beam. In most situations, you’ll need to solder in a resistor to use them.
Jeff, I’ll try and post both external and internal (how I wired it) headlight pictures for you in the next day or two. I still have the ditch lights to install but I need to install the ditch light housings to the front and back ends before I do that. There’s going to be quite a bit of wiring before it’s all said and done.