Wondering what I am not doing LCRX

Attached is a PDF with the Lionel LCRX wiring diagram. You might try incandescent bulbs for testing to make sure it is not an issue with the LEDs. Note that with pins B and L jumped, Cab lamp is controlled by AUX-2. Without the jumper pin E is the front and pin F is the read headlamp controlled by loco direction.

Here is the Lionel Supplement 38 wiring diagram for the LCRX. The LCRX is typically used in a B unit dummy to provide couplers and lights.

Ron,

Check this out:

   LCRX led light problem

It appears that the LCRX light-driver triacs are designed to drive lamps.  You need to trick them into thinking that your LEDs are actually lamps.

Mike

You need .01uf capacitors across the lighting outputs to drive LED's.  However, as i recall, the LCRU versions have "flexible" polarity of the lighting outputs, so to use LED's you also need a bridge rectifier.  Pretty sure the LCRU has that issue as I used one to automate a car and had to figure out why it only worked half the time.

@PennsyTurbine Thanks for the PDF's.  I had the one which came with the board. Just like learning to reverse the polarity of the LED with ERR boards, the secret handshake often takes a while to learn.

@Mellow Hudson Mike   I saved the thread and will give it a try, GRJ seems to have figured out the trick, I will need to check and make sure I have the right resistors (570 1/2W as well as a 680 1/4W) on hand and will also hook up a standard 16v lamp to see if that works.

@gunrunnerjohn  I can add an .01uf , is this is place of the 570 1/2 W resistor you recommended years ago on an old thread?

This is in a F3A trailing unit that I added a RS Commander along with the LCRX. The old boards were toast and had been gutted years before.

I have placed (2) 3mm LED's in the holes normally used for the engineer figures for cab lights, and will be using a 5mm in the headlight bracket on the PWC series F3's.

This has worked well with ERR CC, DC commanders and RCDR's, so when I get it figured out, it will be similar to the other engines upgraded in how controlled and works.

All of the aforementioned units have a fixed polarity for the lighting outputs.  The triggering of the triacs for the LCRU1 and LCRx apparently randomly trigger the triac quadrant so that the polarity of the output will change at succeeding power-up cycles.

John,   You mention a bridge rectifier for the LCRX, would this be between the leads from LCRX and the LED?  I have tubes of the BR used on the LED passenger car lighting boards if they will work.

Correct, you'd have the .01uf cap across the lighting outputs, this causes the triac to trigger.  Next you have the bridge between frame ground and the lighting output, the DC outputs of the bridge rectifier feed the 470 ohm resistor and the LED in series.  It's a lot of parts to get LED lighting, but with the oddity of the random polarity, it's the way you have to do it.

The reason you didn't need the .01uf cap on the ERR stuff is it's included in the design of those boards.

John,  Would one of the LED lighting boards instead of the BR in the mix work?  If so, that makes for a much neater package and about the same effort to install.

Well, it would be a lot bulkier than the bridge, and you still need the .01uf cap across the lighting output.  It should work fine however, just make sure you adjust the maximum current for 20ma or less for the LED.

Thanks John,  This is a dummy F3A with the LCRX in the fuel belly and RS Commander on rear shelf. The LED board will fit nicely on front shelf.  The cab interior masks the shell so all that will be seen is the cab light glow.

I made those diagrams 600 years ago using Excel (ha). Cracks me up when I see them. The dirty trick for LEDs was to run a pull down resistor in parallel with the LED and it’s dropping resistor. There are probably diagrams showing it somewhere out there. The polarity flip was controllable and repeatable from what I remember. I can’t remember if it was flipped by cycling AUX-1, 0. I had a caboose or two with bicolor LEDs that could change color on command.

I never chased it any farther than finding out that it seemingly randomly changed polarity.  I never saw this when they were used as intended with incandescent bulbs, it was only when I found one in my junkbox and used it to automate a hot box reefer than I found out about the polarity reversal.

Courtesy of the old Internet Wayback Machine:

http://web.archive.org/web/200...sky.com/freight.html

Some of the links still work and the old diagrams help explain the odd output behavior. I forgot that the polarities flopped around with the momentum buttons too. I may have to dig one of these out to play with again.