Hello Everyone,
I recently bought an Athearn Genesis GP38-2 with a soundtraxx decoder fiitted and I want to take out the bulbs that came with the loco and replace with LEDs.
Now I understand that the bulbs are 1.5 V, at least they glow quite bright when put on a 1.5V battery but they did not have any resistors between the bulbs and the decoder.
According to the Soundtraxx manual you need resistors between bulb and decoder. So are these decoders that are fitted in Athearn locos a special ' one off ' for Athearn?
If I fit LEDs to this model do I need to fit the normal 1Kohm resistors or not ?
Any advice would be gratefully received.
Kind regards Colin Cambridge U.K.
Colin,
Good question, not sure I have an absolute answer for you. generally, yes, the Tsunami's require a resistor to protect the LED...
But some don't. I recently wanted to add backup lights to a couple of Blackstone C-19s. These use the Micro-Tsu-750 decoder, but in a different, factory form factor than the aftermarket version that comes shrink-wrapped. For some reason, I came to the conclusion that it didn't need a resistor, but decided to call Durango to confirm that finding. At least on some of the special factory Soundtraxx boards, resistors are carried right on the board.
Whether this applies to your GP38-2, I don't know. I suspect it's the case, given the 1.5 volt rating of the bulbs. I recommend confirming that with an email to Soundtraxx support. There are also some docs for the specific aftermarket Tsunamis there, which could also prove useful
Mike Lehman
Urbana, IL
The light output tabs on the Athearn / Soundtraxx board are regulated to 1.5 volts to drive the bulbs directly - they will not drive LEDs.
If you look carefully at the board (top or bottom, I forget) - there will be a small pad labelled +14. Use this pad as your common (blue wire) to wire your LEDs. You will need to use a resistor (1000 ohms is common to use) with each of your LEDs.
The function pads (white, yellow, green, violet) will still be the same as they are just a current sink to the base voltage.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
If all else fails, follow instructions. The SoundTraxx documents are right at the SoundTraxx site.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I agree, check the documentation, but there are usually multiple voltages with using different pads on the board. But, I like the bulbs, I'm likely in the minority, but to me they look better.
Richard