RailPro > Finished RailPro Installation Examples

Athearn U50 Install

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Espeelark:
I've started an install on an Athearn (Southern Pacific) U50. I'll update this post as I move forward.

After removing the shell, I removed Athearn's stock PC board and all grain-of-wheat light bulbs. I will replace the bulbs with LED's. Note - I use 15 mA or 20 mA LED drivers with the LEDs as opposed to resistors.

Here's a photo of the stripped down chassis.


There is a grey wire coming from each of the four trucks on each side providing track power, so four wires per side for a total of eight. You can see them sticking up in the above photo.

Next, I cut a piece of PCB bread-board to make it simpler to connect all of the wires. In addition to the normal forward/reverse headlights, I'm going to install SP's typical oscillating headlight. Here's  a picture of that PCB board installed. Note that I cut-out a couple notches into it to fit around the screw posts that held the factory PCB.


Here's a close-up of the PCB. Here I've soldered the track power leads to separate chases on the PCB. I've separated them by one PCB chase just to help insure no adjacency shorts. I also fed the blue and orange motor wires up through the PCB.


I plan to install the LM-3S just forward of the PCB.
The Scale Sound Systems paired speakers are also installed at this point. One conveniently uses a pair of screw posts that held the original factory PCB. The one in the rear is bigger and sits on the chassis frame with a piece of double-sided tape. I plan to wire these in series.

faithie999:
can you send a link to the LED drivers you use?
why do you prefer that approach vs resistors?

thanks
Ken

Espeelark:
Hi Ken,
I originally used 20 mA current limiters / LED drivers from Lighthouse LEDs. Here's the link to those:
https://lighthouseleds.com/20ma-led-current-limiter-driver.html

I wanted to tone down the intensity of the LEDs just a skoshe so this time I'm trying 15 mA current limiters / LED drivers from Mouser. Here's the link to those:
https://www.mouser.com/ProductDetail/Diodes-Incorporated/AL5809-15P1-7?qs=9BjnSzo86S8n7L%2F6RAZJmA%3D%3D&countryCode=US&currencyCode=USD

As to "why" I use them, I guess it's because I don't have to worry about determining which size resistor to use. With that said however, a resistor is just fine too because the input voltage will always be the same coming from the LM-3S modules.

Regards,

gregeusa:
What is nice about the limiters, no calculating resistors, and you get a constant current no matter what the supply voltage, nice simplification for installs. Bought about 50 of these years ago... I even have them in surface mounts for my Z scale..

faithie999:
thanks for the info!

Ken

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