# Bachmann K27 class lights led change out



## Lake Valley #1 (Dec 31, 2012)

I need a bit of help here since I don't want to destroy anything. I wish to change out the orange looking leds in the class lights on my new K27 to white leds, and need to know where and how to begin; do you pull off the smoke box cover, or just separate the top of the class light from the bottom part; or do the class lights pull out of the smoke box cover? If the smoke box cover needs to be pulled off, how does one go about that? All I can find is that it can be done, but not how to do it. Thanks guys and gals. Jeff


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## Lake Valley #1 (Dec 31, 2012)

Never mind, I figured it out.


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## San Juan (Jan 3, 2008)

Just a recommendation. Look into Golden White LEDs instead of White LEDs.

Golden White looks great on large scale trains. Looks just like a bulb to me. Probably the closest current LED color to an incandescent. I've used them on my Bachmann caboose, and a 1:22.5 Bachmann 2-8-0 converted into a K-27.

I purchase my LEDs from Ulrich Models. Here's a link:

3mm Golden White LEDS 


Here's the Golden White LEDs in the caboose...I didn't like the orange ones they came with:









Here's Golden White LEDs on the K-27 (#461). The K-28 (#473) has incandescent bulbs.


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## Lake Valley #1 (Dec 31, 2012)

Great looking lights! Thanks so much for the heads up, I've been getting stuff from Big Lots here in Odessa, that seems to be about the right color, but I'll sure go look at the link you so graciously provided. Thanks again, Jeff


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## East Broad Top (Dec 29, 2007)

I use the "warm white" LED Christmas Lights. There's a subtle variation between brands, but most are pretty close to an incandescent bulb. I do have a bottle of yellow translucent paint just in case they're a bit blue. (This does not "fix" the "cool white" LEDs which have a distinct blue cast to them.) 

Matt, I'm over in Mancos at the moment. I'll wave on my way home tomorrow. Someday I'll get into this part of the state in the Summer... 

Later, 

K


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## San Juan (Jan 3, 2008)

Posted By East Broad Top on 16 Jan 2013 06:59 PM 
Matt, I'm over in Mancos at the moment. I'll wave on my way home tomorrow. Someday I'll get into this part of the state in the Summer... 

Later, 

K







Thanks. Although I'm in California right now. 

I plan to get out to Colorado this summer though. If you are in the area during the summer send me an email. We'd love to show you the layout.


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## Lake Valley #1 (Dec 31, 2012)

I opted for the waterproof battery operated set from Big Lots...they look really good to me. Just white enough to throw a good beam from the headlight, but I did have to put in an adaptor because these are an epoxy dipped item and then move it in and out of the reflector for best focus. I used the same thing in the Class lights and they are pretty good looking there also. Everything looks like the pics on both of your engines. I'm pleased, even if I did have to fiddle about with these as they are not shaped like a standard LED. I paid $8 for a 20 LED set, and cut 'em loose from the string; figured out which lead is the cathode and went from there. I think I'll use a few in my bashed B-mann passenger car and mail cars, too. I may use them in the caboose kerosene lamps also as the shape is reminiscent of a kerosene lamp flame.


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## beavercreek (Dec 12, 2008)

Hi
I want to change the leds for the marker lights and the headlight/back-up ight.
Does anyone know the voltages that the K27 circuitry suppliesto these?
I will be using 3mm warm white leds for the markers and 5mm for the headlight/back-up but am not sure of the specs of the leds I will have to use and the power handling that they will have to be.


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## East Broad Top (Dec 29, 2007)

I'm pretty sure they feed track voltage to the LEDs, with whatever circuitry already built into the on-board control electronics to limit the current. From what I can tell from the wiring diagram, they use a series of resistors and transistors--my guess would be this is a current-limiting circuit which works on a variety of input voltages, feeding a constant current to the LED as opposed to simply relying on a dropping resistor which isn't as stable with varying voltages. 

It shouldn't matter to just swap out new for old. Just clip the wires going to the LEDs, and solder the new one in place. If you can, figure out which wire goes to the anode vs. the cathode so you get the new LED in the right way. Otherwise, take a guess and if it doesn't light up, solder it the other way. 

If you bypass the on-board electronics to control the LEDs, then you'll want a dropping resistor in series with the LED. I use 1000 ohms. (You could also use a current-limiter like a CL-2 in place of the resistor.) 

Later, 

K


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## beavercreek (Dec 12, 2008)

Thank you for the helpful input Kevin
I will use some 5v-22v 3mm leds with inbuilt rectifier and that will help with what ever voltage/polarity might be at the wires. I have used these for rolling stock interior lighting where polarity might be an issue.
Your railroad is great! a goody!


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## San Juan (Jan 3, 2008)

Posted By beavercreek on 24 Jan 2013 01:24 PM 
I will use some 5v-22v 3mm leds with inbuilt rectifier and that will help with what ever voltage/polarity might be at the wires. 

Not sure those will work, or be bright enough. The Bachmann LED connections are already at the correct voltage reduced by the circuity in the loco. So you probably need a typical 3 volt LED. 

On the Bachmann caboose I swapped the factory LEDs for new ones without using any resistors. I used the existing circuitry without any issues. Was quite simple to do. Longest part was waiting to receive the new LEDs


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## Greg Elmassian (Jan 3, 2008)

Actually, the Bachmann LED connections are already at the correct AMPERAGE, LIMITED by the current regulator circuitry in the loco. 

If the LEDs you are using will operate at 5 volts, it's possible that the Bachmann circuitry has likewise reduced the effective supply voltage too low, but probably not. 

I'd take Matt's advice and use "raw" LEDs.... the supporting circuitry is already there... 

Greg


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## beavercreek (Dec 12, 2008)

Thanks for the good input Matt and Greg.
I have quite a few of these rectified leds (they are really useful when there is not enough time to rig up my own) so will have a go with them but first test them on a 3 to 5 volt feed to see if they light up okay. If not it will be some straight unrectified leds. There are good supplies of those over here so that won't be too much trouble.
I like your caboose lanterns Matt, just might try those as well!
I have been using the ready made rectified leds on my 'dress-ups' on my fleet of Bachamann Annies as I convert them into 'poor man's' D&RGW 'T-12' locos


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## Greg Elmassian (Jan 3, 2008)

Beaver (ha ha, what is your name by the way?): just curious, is there a full wave bridge rectifier so the LEDs will work with any polarity DC input? 

Normally the add-on is a resistor to limit the current and allow you to have a "12 volt LED"... 

Always want to hear about different options. By the way, there's many different "definitions" of warm white now, so more and more LED suppliers are specifying the color temperature in Kelvin, I find the 2700 degree warm enough to look good in 40's to 50's stuff... the golden white is "warmer" and more yellow. Some "warm white" leds are 3500 degree... they start becoming "harsh" around 4,000 degrees (in my personal opinion). 

Regards, Greg


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## beavercreek (Dec 12, 2008)

Hi Greg

My name is Mike and the name 'beavercreek' is taken from my railroad 'The Beaver Creek Railroad'. So named due to my good lady's maiden name being Beaver (no sniggering at the back) and also the fact that it is loosely based on the Rio Grande with the 'freelance' Beaver Creek line linking in. There is a real place called Beaver Creek which is near Eagle, Colorado (and is now just part of the Vail ski and residential complex) and of course very near to the old D&RGW line.

Anyway back to the LEDs. I usually want lighting that can be operated under any polarity and DC/AC so usually make up my own from 5-19v warm white (around 3000k for steam era 30s to 50s and around 5000k for 60s diesels) with a rectifier and/or resistor.

I was feeling a little lazy one day and was online searching for some ready made flickering 'fire' leds and came across 'Evans Designs'. I also saw in passing that they do different sized leds that are set up with rectifiers and resistors and are available in different colours and for different voltage requirements. So recently I ordered a few. They are not as cheap as doing them myself but for about 10 I was happy to get them in. They are practically indestructible and the supplier guarantees them with replacement if they fail before the expected lifespan.


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## Greg Elmassian (Jan 3, 2008)

So, can I assume your "rectifier" is a full wave bridge? Otherwise I cannot see how it will work on reverse DC polarity. 

Regards, Greg


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## beavercreek (Dec 12, 2008)

Yep a full wave bridge. I did shorten the name from bridge rectifier, I must be more precise when on this forum. I usually am on the GScalecentral forum and we are a little more free and easy over there with our terms of reference etc. Us Brits can be very laid back you know







.


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## Greg Elmassian (Jan 3, 2008)

There's people who equate "rectifier" with a single diode, so I wanted to clarify. I normally reserve rectifier to a FW bridge myself, but technically a rectifier can be one or more diodes... or a single one depending on who you talk to. 

I'm old enough to have used germanium rectifiers... (actually tubes too) 

Greg


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## beavercreek (Dec 12, 2008)

Jeees you must be ancient Greg....Only kidding, you are younger than me! 
I remember in 6th form (18years old) at school, we were given a computer from the University nearby. It was just a massive lump with direct punch card input (no keyboard), no storage and readout was from numerical thermal tubes. We were impressed at the time but soon realised it was very limited and nothing like the computers in the film 2001! .... oh those days of years before before microprocessors ....life may have been simpler but it also seemed to pass by slower too!

Enough wallowing in nostalgia.









The bridge rectifier that Evans Designs use in their 'ready made' led leads is pretty small in size (and smaller than I use when I make them up myself) so they fit better in cramped spaces.

On a different LED application, there is also a good supply over here of warm white E5,5 screw LED replacement bulbs (the size that Piko, Pola and LGB use) which also have minute bridge rectifiers in the base (they are still the same size as the filament bulbs) so that you do not have to worry about polarity. They work from 5v to 22v and cost us about $1.50 each. With a little sanding of the surface they throw a good light all around. I expect that you also have them over the pond.


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## Greg Elmassian (Jan 3, 2008)

have not seen them packaged as such... do you have any links? that would be cool to investigate, great idea... I do "stock" surface mount FW bridges and the CL2... I also model in Z scale so I have need of really small stuff. 

Regards, Greg


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## beavercreek (Dec 12, 2008)

The best source of them in UK is from German ebay:
http://www.ebay.de/sch/i.html?_trksid=p5197.m570.l1313&_nkw=e5,5+led&_sacat=0&_from=R40

But there seems to be a source of slightly lower voltage ones in US . They describe them as having built in resistor but I am not sure that they have inbuilt bridge as in the German variety, they do say that they can be used with DCC and AC so suppose that they also have the bridge:
http://www.trainaidsa.com/support-leds.shtml
Hope this helps

EDIT
Just read that the LEDs from Trainaids need their connector wire that includes the bridge rectifier if being used with AC etc.


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## Greg Elmassian (Jan 3, 2008)

Yeah when they advertise ac and dcc you can tell they don't have a bridge they are using the diode properties of the led to handle the ac although electric engineers will tell you the piv voltage of a led is usually too low to be used alone on ac.... but they usually work ok


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## beavercreek (Dec 12, 2008)

I tested a couple of the ones sourced from Germany and also the ones from Evan's Designs in US at 20v switching the polarity at 3amps and no problems at all. So the bridges in those are fine...don't think that I would do the same without the optional 'bridge' wire for the Trainaids variety!


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