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Replacing Headlight Bulbs or LEDS and Stuff

Started by jonathan, December 08, 2012, 06:49:30 AM

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I've been tinkering with Bachmann Locomotives for about 6 years or so.  On the steam side, about 90% of these locos are made in a similar fashion:  split frame construction, with all the critical working parts sealed within the frame halves, and some t-nut screws holding the frame halves together.

The "replacing-the-headlight" question has come up again, so I thought I would, once again, post a few pics on how I go about replacing bulbs.  BTW, I haven't had to replace a bulb on a diesel, yet, so I can offer no advice about that.

Anyway, here is a first generation Spectrum 2-8-0:

I thought I had a first generation already, but this one has hard foam rubber lining, and WHITE Connector Plugs:

I had only seen orange connector plugs until now.  Amazing how just a decade or so has made this once cutting edge technology now look like a Neanderthal installed the electronics:

This is not part of the headlight issue, but while we're in here, I went ahead and attached an LED and 1K ohm resistor to the old fashioned dummy plug.  This will become a reverse light.  When I finally get around to making my home layout DCC, I can easily wire in the light to the new decoder.  For now, this works great:

OK, on to the headlight... This older model came with a conventional bulb, so I'm going to replace it with an LED... aaaaaaand slightly modify the headlight to help with the brightness.  By putting the loco on the track, and using an LED/resistor as a tester, I was able to determine the Green Wire is Positive (+).  This is important for LEDs.  The positive side of the LED must coincide with the positive side of the track (right when moving forward).  Elsewise  :) , the light won't light, man.

Notice how I wrote, in pencil, my findings on the top of the motor, right where I cut the headlight wires.  One less thing I have to remember while I work.  

Now, I failed to take a pic when I took the frame halve apart, but MOST of the time, the bulb won't release from the frame halves unless you open them up.  The t-nut screw removal is easy.  Puting all the motor pieces back the way you found 'em can be a little unnerving the first time.  I'll look for a pic I have of the frame open, and post that later.

Here is the headlight itself:

The big, clear cylinder is the light tube that transfers bulb lumens to the headlight.  I throw that away.

Drill a 1/8" hole in the back of the headlight and press fit the 3mm LED into the back.  I usually add a little white glue for good measure:

The original headlight lens will no longer fit into the headlight.  I use to cut the lens in half with a hobby knife.

Now, I make a visor with 1/4" brass tube and add a 14.5" lens from Detail Associates.

That's all I have time for at the moment. In the coming days, as I complete this loco, I'll post more about headlight replacement/installation.




Very nice Jonathan.
Here is a little more info to go along with what he says.

Notice the multimeter.



Thanks, Rich.  That's a good primer on LEDs.

Just found a few more pics that may be helpful.  Here is what the motor/gearing looks like when the frame halves are separated:

Of course, this is a 2-8-0.  Don't think the 2-10-0 has a drive belt.  As you can see, it's a little  tricky, but it you take your time, you will soon get use to taking these babies apart. Too bad one must take these apart to get at the headlight, but so it goes.

This is what the headlight looks like with a LED stuck in the back.  From normal observation distances, you can't see the wires/leads:

The nice thing about the 4-8-2 Mountains:  the smokebox covers come off.  makes it easier to change/install lights.  They actually came with LEDs, but I moved 'em around a bit:

Pulled the LED out of the frame halves, as mentioned above:





Sorry this is taking so long... I'm making some serious modifications as we work on the headlight.  Turning this Connie into a locomotive that actually existed.

Today I added some wire, to bring the connection to the front of the frame.  There is some dead space between the frame and the smokebox front.  So, this is where you have room to intall a resistor and connect the headlight wires when all the other projects are completed. 

Notice, I ran out of green scrap wire. So, I'm substituting with blue.  Remember, red is negative (-).  I don't know why, but it is recommended the resistor connects to the negative side of the LED.  I used some shrink tubing and masking tape to keep the wires safe and out of the way, in anticipation of the shell going back in place:

The headlight is prepared and ready for it's LED in the back:



electrical whiz kid

Where were guys like you when I first got into this stuff?   This post is a great gift for the guys just coming on board and even a lot of the guys that hav e been here for a while now; myself notwithstanding.  One can learn-even something little-from most things in this world; a post like this one makes it even so much better.  Keep up the great work.
Rich C.


Thanks, EWK.  Happy to share what I know, which isn't that much.  Hopefully, some of it is helpful to others.  :)

OK, I'm ready to start painting, after all the modifications.  Before painting, now would be a good time to test the headlight, in case there is a problem.  Better to know now than after reassembly.

A simple LED tester is a 9v battery with a 1K ohm resistor attached to the negative pole.  I bent out one of the tabs, put in the resistor, and bent the tab back:

As you can see, I've raised the headlight, but it's easier just to put the headlight back into it's original slot and reglue.  I had to drill a couple of small holes to run the LED leads:

And a little black paint helps hide the back of the LED:

I cut up a plastic coffee stir stick and covered the LED leads, to prevent shorts by touching each other, or the front of the motor assembly frame:

Zounds! It works!

Here endeth my speech.  Thanks, you've been a great audience.  Tip your waiters and waitresses.




If anyone here wants to keep this discussion nearby, store the URL in Favorites. If Bachmann does not redo the site, you will have this discussion handy.
The best solution for keeping this discussion handy is to save the page to your PC as a HTML document.
Upper left, click File. Click, Save Page As. Remember where you saved the file to. You would be surprised at how many have trouble at this point.
When you click on the file in your PC, the page opens up just like it did the first day you saw it. Many people are not aware of the fact you can store the page to your PC. Now any links on the page may not work in the future but you have the basic data you need.
Your PC is a powerful device. Many fail to take advantage of it.


electrical whiz kid

One of the things I would like to do is to get a light source to the marker lamps.  I am toying with theidea of using optic fibres to accomplish this, possibly cleaning off the backs of the jewels, and just runing the fibre from the headlamp to the marker, and entering via the side closest to the body.  Has anyone done this?   Feedback will be appreciated.
Rich C.



Yes!  This has been done.  I have read internet articles about it.  I can't send you to a source, as I didn't save any of the links.  Not something I intend to do in the future.

There are, in fact, very expensive models available, that have lit their markers.

Also, there are unbacked jewels available from Utah Pacific.  One could simply drill a small hole through a marker, intall unbacked jewels, and insert a light fiber from the locomotive shell, and voila.

If you try it, please post some pics.  That's extreme modeling to be sure.  Very cool, but too much for me.




Making a point here.

Lights on the front of a locomotive are NOT, repeat NOT  "marker lights".  Sadly, a common error among model railroaders and railfans.

They are in fact "classification lights" or "class lights" and are only lit when the train is either an extra (White) or to indicate a second section is following or that the train is a section (Green).  If there are three sections to the train, the first and second sections will display green classification lights while the third will display no classification lights.  During daylight, Green and White flags are used either on their own or in addition to the illuminated class lights.

Marker lights are the red tail lights placed on the last vehicle in the train be it a passenger car, a caboose or a freight car.

In the rule book, a train only becomes a train when the markers are placed on the last car and ceases to become a train when the markers are removed.

Them's the rules guys.  Or were.  So let's at least try to be accurate.  It saves a lot of confusion.


I couldn't let this thread go, without posting a few pix of the completed locomotive, with the lights working.  It's like a switch I need to flip or I can't move on.  Perhaps, I'm in the Twilight Zone.  :)

Anyway, here's a few shots of the Spectrum Connie, now turned to an E-27ca, or a reasonable facsimile.  Only thing missing is a whistle, which I'll find at the next train show.



Addendum:  I promise I'll try to remember "class lights" vs. "markers".  That one gets me all the time.  ;D

Jerrys HO


You have done a great job with all your projects. Now you have me getting ready to order my first big steamer. Just have to figure out which one now.




Thanks for this article.  I've saved it under "favorites".

It was timely for me.  I am in the middle of a project of installed diodecontrolled directional lighting in my N-scale locomotives.  So far, all converted locos have been Diesels, but was thinking of tackling some steam locos too.

The problem with steamers (especially in N) is the headlights are so small light bulbs present a problem.  LED's are the answer, but I know they required a resistor, and didn't know what value to use.  Thanks to you, I know to try 1K resistors.

Great pictures, too!