led headlamp install in 18046

I believe any of these would be a direct LED replacement for your locomotive:

http://stores.towncountryhobbies.com/led-1447ww/

This place has different LED lenses. Scroll about half way down to the 14V LED bulbs and select the E10 Screw Base Focused Led Bulbs Warm White or E10 Screw Base Inverted Lens Led Bulbs  Warm White depending on orientation.

http://www.superlumination.com/trainbulbs.htm

 As for command control, ERR has the product line you need. http://www.3rdrail.com/err-3rdrail/ shows that your 18046 should use the AC Commander

Keal.....I see your Loco has the early TMCC LCRU board in the engine so it should work fine with a original 14 volt bulb. How about replacing with a new one? Here is the bulb from Lionel $2.00 but their postage will be much more than that. Also if a wire burned that might need to be repaired. Looks to me like the boiler front can be removed with one screw.Take a look. A led needs a resistor and diode added. Since you are not in to soldering perhaps one of the vendors shown above could help. 

https://www.lionelsupport.com/...72-9cf0-1491792dd2e9 

Richard

No need to order from Lionel and pay shipping for an original style tungsten fillament bulb. Just get a standard 1449 bulb from any supplier.

However, my LED recommendations above still stand.

Remember, an LED with the original LCRU will need a little extra.  The polarity of the output light circuit changes randomly on startup.  So, unless you add a bridge rectifier to the mix, you'll only have a headlight half the time.

thanks GRJ,  but still need current limiting resistor. 

Correct, you still need current limiting, the bridge rectifier is just to insure the LED always sees the proper polarity.  You can use a very small bridge rectifier, you're only handling milliamps.

Looks like I goofed here a bit - I mistook the OPs request for TMCC to be that of a TMCC upgrade and completely missed the fact that this locomotive has an existing LCRU in it!  Even 3rdRail listed the AC Commander for this specific locomotive further cementing the direction I was heading...

It never crossed my mind that the headlight wasn't AC track powered. I am not sure how any of my LED recommendations would behave on DC; the specs don't list a polarity. I would wager that the base would be -DC and that the tip would be +DC. With the screw base of the original bulb being AC common, and the wire being either the correct or incorrect polarity (based on LCRU behavior), I don't see how a rectifier would help unless you isolate the screw base as well (Maybe my morning coffee hasn't kicked in yet and I'm missing the obvious). I also don't understand the need for a discrete current limiter (resistor) for any of the drop in replacements - that is internal to the unit. @gunrunnerjohn, can you smack me over the head with a 2x4 and set me straight?

A bridge rectifier being fed with AC or either polarity of DC will always output a fixed polarity of DC on the output +/- terminals.  Given that fact, if you have an unknown source of power, a bridge rectifier will turn it into DC with a polarity you can count on.

FYI, most TMCC stuff outputs half/wave track power in command mode, the LCRU just happens to not control which half wave side it puts out, it's random.

I understand what a rectifier does, I just don't understand how to implement your recommended rectifier here. It was explained above that the LCRU always outputs either the -DC halfware or the +DC half wave.

I've drawn out the scenario here as I understand. Again, as I stated above, in adding the rectifier, you need to also isolate the bulb socket form the boiler face where as AC common will short out against the opposing half wave rectified DC. I still don't see the need for discrete current limiting with the direct replacement LEDs. Please excuse my crude drawing skills and the inconsistent AC phase on the waveforms.

All.....One way to avoid all this is to switch to a LCRU-2. I just finished using one in a AC F-3 postwar and it does not wake up in the wrong polarity. Pro-Cost is half of a LCRU-1 $80.00!  ($40 or $20 depending on when you get it) Con- is you have to make up the eh connectors although some come with a partial harness. Also you can set your features just like a R2LC. I am using resistor diode combo with a .01 cap just for good measure. Works.

Richard 

Pretty sure the LCRU-2 has the same random polarity to the lighting outputs.

Yes, you have to isolate both sides of the LED when you use the bridge rectifier.

GRJ.....Just powered the one next to me up and down five times . Works every time. Maybe I just got lucky.

Richard 

Yep, I think you may be assuming things.  It's been a while since I worked on either an LCRU or LCRU2 engine, but I thought the LCRU2 had the same issue.  FWIW, I had an LCRX in a hot box Reefer to give it TMCC control, though I was pretty smart.  It worked a bunch of times and one day it wouldn't work!  It has the same polarity issue.

I'll wait for the final returns, maybe the LCRU2 doesn't swap the polarity, but I thought it did.

GRJ....I usually don't post on one example and do not post unless I have personal experience with a topic,but I've been working with this conversion (F3A powered and sound in dummy F3 A ) for a month or so and once alive the LCRU 2 LED has always worked first try. BTW the RS 3 sound system works and sounds good even has road name and engine number correct NYC 2344. All parts were available This past November. 

Off topic, I have the boards and parts in for your smart mother board. I plan to try my hand at surface mount soldering soon, Those three caps next to the R2LC look like a good place to start.

Richard 

Sorry NYC 2333 is correct. 

Richard

Good luck with the SMT parts.  it's not actually that difficult, but it does take mastering the technique.