Adding Lights to Genesis Board

[drisdon]

I have an Athearn Genesis GP38-2 that I attempted to add rear ditchlights using the Athearn board, just added the pair of bulbs (recycled from another Athearn loco) in the same manner as the front ditchlights it came stock with to the next available function connection. But, when I turned it on for the first time with Railpro I cannot get them to light, what am I doing wrong?

I also added a keep alive and it really makes that loco run smooth! Wow!

Dan risdon

[PerezBill]

The 1st thing I would question would be do the connections on the board function where the lights are connected? 2nd thing would be to try to see if RP is connected to that connection where the lights are. I would make the assumption that you already know the bulbs are good. That's where I would start.

Bill

[drisdon]

I tested the bulbs before and after installing into the ditchlights, so that's good.  How would I test the other function on the board to know it's active?


The tweezers show where I added the extra lights, I also soldered all the wires to the board as function one had a short, once soldered short resolved.  The clips are probably faster, but do not provide a good connection.

Thanks,
Dan

[PerezBill]

The only answer I can provide would be to remove the board from the locomotive and look at the traces on the back side of it. Make sure they go somewhere and are not disconnected/cut. With that said did you check to make sure that you wired the +  and - correctly. I don't remember if bulbs care about that though. There is also the possibility that there is a resister on built into the board that is so high the bulbs won't light with the available power supplied to them. You may want to consider wiring them directly to the decoder and bypass the board. That way you know what you have and can eliminate a possible issue if the board has a bad circuit which can sometimes be hard to diagnose.

[drisdon]

KPack solved the mystery, the 9 pin harness only supports four functions, front headlight, rear headlight, and 2 front ditch lights.  So I have to hard wire the rear ditchlights.  Will 1K resistors work with the Athearn bulbs?  I usually use LED's so not as familiar. 

Dan

[KPack]

Dan, I'll respond here rather than email so we can get the information out there for others. 

I've never wired a 1.5v bulb to a resistor because I always change them out in favor of LEDs.  I'm honestly not sure of what resistor to use in this case.  For LEDs I use a 1K ohm 1/4 watt resistor.  LEDs I believe typically run at 3V or so, so perhaps a bit bigger resistor for the 1.5V bulbs?

My vote is to start your LED conversion early and just pop two LEDs in the ditchlights.  That way you only have four more to change later.

-Kevin

[drisdon]

This is not a bad idea...and maybe change the rear headlight at the same time.  At least when viewed from the rear the color would all look the same.  It's not like I don't have the LED's, I just thought adding 2 bulbs would be easier.  When I connected everything yesterday I really didn't like how dim the headlights were with the bulbs, so LED's would definitely brighten it up too and make it much longer lasting and uniform.

Thanks for adding to the workload!

Dan

[KPack]

Thanks for adding to the workload!

Just doin' my duty. 

It just makes more sense to put the lights in one time....if you do bulbs you'll have to change them out, and you won't be happy with how dim they are.  Do it right the first time and save yourself the trouble later!

-Kevin

[Alan]

If you do decide to use 1.5v bulbs with LM output you will need a dropping resistor. If the bulbs are 12v or higher then no resistor needed.

To determine the resistor value needed you must know how much current the bulb draws at 1.5v either by measuring it or from the manufacturer's specs. Once you know the current then use Ohm's Law to determine the resistor value.

Resistor value = (track voltage - bulb voltage) / bulb current. For example if the bulb draws 15mA at 1.5v then the formula is (14.8 - 1.5) / 0.015 = 887 ohms. Closest available resistor value = 1000 ohms. Higher value resistors will make the bulb dimmer.

Once the value is determined you need to calculate how much power (heat) the resistor will have to dissipate. The formula for that is (track voltage - bulb voltage) * bulb current. For our example 15mA bulb the formula is (14.8 - 1.5) * 0.015 = 0.2 watts. Closest resistor rating is 1/4 watt (although that is cutting it close, better to use a 1/2 watt unit).

Kevin is right. Bulbs have a short lifetime, LEDs have a very long lifetime. Go with LED unless you really need the incandescent "look" which is totally understandable on a locomotive. Prototype are not LEDs (yet).

[Dean]

KPack solved the mystery, the 9 pin harness only supports four functions, front headlight, rear headlight, and 2 front ditch lights.  So I have to hard wire the rear ditchlights.  Will 1K resistors work with the Athearn bulbs?  I usually use LED's so not as familiar. 

Dan

Couldn't you use the six pin connection to get more outputs?

[drisdon]

Yes, that is the solution, it cannot be just added to the board like I already tried.

I think I will try the bulbs as they are already glued into the ditchlight housings. They will instead attach to the outputs off the 6 wire connector.

Dan

[drisdon]

Bulbs didn't work for some reason, so tonight I stripped out all the bulbs and replaced with SMD 0402 LED's, next step will be all the resistors and hardwiring the module in eliminating the Athearn board.

Thanks for all of your input it was very helpful even if it tripled the amount of work.

Dan

[KPack]

You'll be much happier with everything hardwired.  You'll have much more space (probably enough to get a decent speaker in there) and you'll be able to get all the wires nice and tidy.  It's worth the effort!

-Kevin

[PerezBill]

Like he said ^.