I have 2 Athearn RTR units (GP35 and SD40) along with a Genesis unit (F45) which i want to put LED lighting into by using 2 3mm LEDs with some fiber optic strands. Is there a way to install these with the original lightboard? I tried on my GP35 earlier and couldn't get any working lights. I was getting so frustrated that I took out the lightboard and hard wired a decoder harness. On the bright side, it still runs great. But I really want to avoid doing a hard wire installation again like earlier.
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Athearn uses 1.5V bulbs. Not enough to light the LED. If you want to use LED's, you have to replace the PC board with a board stlye replacement decoder. It's easier this way then hard wireing in a decoder. Joe
Easiest thing I've found to do for 3mm LEDs is take some appropriate-sized Evergreen or other plastic tubing, cut off a short section and epoxy it behind the lamps. Paint it black if its the lights above the cab, unless you want cab illumination. LED slips in and out, held in place with wire leads the right length putting a little pressure on from behind.
Mike Lehman
Urbana, IL
Is there any way at all I could use LEDs while retaining the original light board? I really don't want to have to buy another decoder that's a board replacement for my next 2 Athearn units just for LEDs since they already have a decoder plugged into the 9 pin socket.
You have to jump over the resistors on the factory board and then use the proper size resistors for the LEDs. If you can solder and desolder surface mount, you could replace the resistors on the factory board with 1K ones and just attach the LEDs to the same terminals as the original bulbs.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy, have you actually done that modification ? The Athearn boards do not use only a resistor to the 1.5 volt bulb - they use a series of diodes (4 on each each end) to create the proper 1.4 volt drop across them. The bulbs are wired across this diode bridge to ensure a steady 1.4 volts to the bulbs regardless of track voltage.
The simplest way to bypass this if you are using the 9-pin plug is to cut the white, yellow and blue wires from the main board and use those (blue common negative and white front and yellow rear) to wire your LEDs direct from your decoder's outputs. Be sure to add a 1000 ohm resistor between the white and yellow wires and your LEDs.
Mark.
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No idea what they have, other than something to limit voltage to 1.5 volt bulbs, the one Athearn RTR loco I have, I did like I do in almost all my installs - ripped out the factory junk and hard wired it. It's sitting in my junk box somewhere. Unlike my early DCC days, I didn't even bother to try and trace the circuit.
Well, "rip out" might be too strong, it has a Loksound Select in in in place of the factory board.
Curious .... if you have no idea what they have, why respond with a suggestion that isn't even correct ?
Because it's not really incorrect? Bypass the circuit on the factory board and use independent resistors. Full voltage less the proper resistor drop to the LEDs. Doesn;t really matter if you are bypassing a resistor, or a diode, or a combination thereof, the key is bypassing it.
My point is, is that you instructed the OP to jump the original resistor and add his own. If he just did that, it still wouldn't work. It IS incorrect.
People come here looking for specific answers. If you haven't done it yourself and don't know the specific answer, why are people still compelled to add to their post count ?
Back to the OP's question. He wants to retain the original light board and not have to splice into the 9-pin harness to light his LEDs. Any way to modify the original light board to get 12 to 14 volts to the resistored LEDs?
I sure don't know the answer, but I would be interested in learning about a possible workaround.
Rich
Alton Junction
Yes, jumper a wire from the pin where the 9 pin harness attaches to the board to the trace for the light connection on the circuit board - connecting the white or yellow wire from the 9 pin directly to the connection at the edge of the factory board. Best practive would be to then slide throught he trace leading to the rest of the junk on the factory board, but a straight bypass wire should work.
Still easier (and cleaner) to just hardwire
Add to my post count? At this point, one extra post is a tiny fraction of my post count, I've been here so long. They took away the display of such a few updates ago. I really don't care. I'm not the highest, and there is no chance for me ever become the highest, based on the last time I saw counts.
When you guys are talking about the diodes on the light board, would that consist of removing the resistors on both ends along with the 4 diodes? If so, I can (possibly) do that.
Removing the four diodes and the resistor won't work on its own because you will then have a bunch of broken links where the components were. There are circuit traces on both sides of the board and under the diodes, so I can't tell the exact configuration. The white and yellow wires feed through the diode bridge along with a small resistor at both ends. There are also two additional diodes for directional lighting and to top it off, the blue common lead also feeds through a pair of larger resistors.
I gave up trying to decipher the traces on these boards long ago - just seems too confusing for what it does.
If you are capable of doing fine soldering, and insist on using the factory board, all you have to do is unsolder (or cut) the blue, yellow and white wires from the main board and use those leads to wire your LEDs. Simple and gauranteed to work right the first time.
I have been toying with the idea to replace the rtr boards with the Soundtraxx MC2H104AT DCC Control-Only replacement board for Atlas, Intermountain, and other models that use a similar design, like Athearn. That was before I found this post:P
So, if I can bypass the board resistors by connecting the LEDs to the white, yellow, and blue wires, would I connect the LED to the board end, or the harness end? To simplify, would I power the LEDs from the board, or the harness, which has either the DC jumper plug or a decoder? Would this work with the Miniatronics 5mm "Yeloglo" White LEDs with the 560 ohm resistors that come with them? And how will I wire the LEDs so I have the same directional lighting that I had before?
CPRail43 I have been toying with the idea to replace the rtr boards with the Soundtraxx MC2H104AT DCC Control-Only replacement board for Atlas, Intermountain, and other models that use a similar design, like Athearn. That was before I found this post:P So, if I can bypass the board resistors by connecting the LEDs to the white, yellow, and blue wires, would I connect the LED to the board end, or the harness end? To simplify, would I power the LEDs from the board, or the harness, which has either the DC jumper plug or a decoder? Would this work with the Miniatronics 5mm "Yeloglo" White LEDs with the 560 ohm resistors that come with them? And how will I wire the LEDs so I have the same directional lighting that I had before?
If you are plugging a 9-pin decoder in the Athearn plug, cut the blue, white and yellow from the factory board (leaving them attached to the 9-pin socket) and wire your Leds to those three loose wires using resistors in series with the LEDs. The 560 ohm resistors will work, but the LEDs "might" be too bright for your liking. Try it and see - most people are now going with 1000 to 2000 ohm resistors with todays bright white LEDs.
If the decoder you are using supports direct LED installation (like TCS decoders) you won't need to add your own resistors. I would recommend the TCS T1-LED decoder for ease of installation. As for the directional lighting, most all decoders default to directional lighting right out of the package.
Mark R. CPRail43 I have been toying with the idea to replace the rtr boards with the Soundtraxx MC2H104AT DCC Control-Only replacement board for Atlas, Intermountain, and other models that use a similar design, like Athearn. That was before I found this post:P So, if I can bypass the board resistors by connecting the LEDs to the white, yellow, and blue wires, would I connect the LED to the board end, or the harness end? To simplify, would I power the LEDs from the board, or the harness, which has either the DC jumper plug or a decoder? Would this work with the Miniatronics 5mm "Yeloglo" White LEDs with the 560 ohm resistors that come with them? And how will I wire the LEDs so I have the same directional lighting that I had before? If you are plugging a 9-pin decoder in the Athearn plug, cut the blue, white and yellow from the factory board (leaving them attached to the 9-pin socket) and wire your Leds to those three loose wires using resistors in series with the LEDs. The 560 ohm resistors will work, but the LEDs "might" be too bright for your liking. Try it and see - most people are now going with 1000 to 2000 ohm resistors with todays bright white LEDs. If the decoder you are using supports direct LED installation (like TCS decoders) you won't need to add your own resistors. I would recommend the TCS T1-LED decoder for ease of installation. As for the directional lighting, most all decoders default to directional lighting right out of the package. Mark.
Ok, thank you! Will this wiring work just the same with the stock 9-pin DC jumper plug for directional lighting? Im running on DC control, and my RTR boards dont have a DCC decoder connected to them yet. Great! Appreciate the input!
No. This is for when you install a decoder. When you install the decoder and snip the blue, white and yellow leads from the factory board, the lights are now being fed straight from the decoder. It won't work the other way around on DC.
The harness is designed as an input for a decoder, not an output for lights.
If you want LEDs in a dc locomotive, just remember that they are diodes whose function is to emit light. So if current idls flowing the correct way, light will be emitted, but if current flows the other way, as in reversing the locomotive, the LED will not light. So, what you would probably want in a dc setting is to wire an LED so that when the locomotive is moving forward, the front LED lights up, and then wire the reverse light to come on in reverse. The way to do this, is after figuring out the correct way to make the front LED light up, install the reverse light with the polarity reversed. This way, when the locomotive is reversed, the front light will stay dark and the rear light will come on.