Early Legacy upgrade to LED headlight problem

LED has polarity, the TRIAC fires a different polarity and states of AC and AC with DC bias. Again, in conventional, the TRIAC tends to fire more AC so the LED lights, but in command the output is more DC biased but still pulsed and happens to be opposite your LED.

Reverse the LED.

The headlight output of the R2LC or R4LC in command mode is half-wave track power, negative in respect to frame ground.

@Vernon Barry posted:

LED has polarity, the TRIAC fires a different polarity and states of AC and AC with DC bias. Again, in conventional, the TRIAC tends to fire more AC so the LED lights, but in command the output is more DC biased but still pulsed and happens to be opposite your LED.

Reverse the LED.

Funny enough I did think about that but then it didn’t even light at all, probably had something else backwards, I’ll double check everything when I get to the work bench

Thanks guys 👍

Ok I know this is sad I’m sure there’s plenty of threads on this but just could find one that matches what I’m doing. Here’s a crude schematic of what I have tried. I am obviously missing something but I don’t understand as I’ve tried reversing the LED polarity with still the same result. Works in conventional but no dice in command.

Does a plain incandescent bulb work connected directly to the lighting output?  Maybe you've killed the lighting triac?

@zhubl posted:

Ok I know this is sad I’m sure there’s plenty of threads on this but just could find one that matches what I’m doing. Here’s a crude schematic of what I have tried. I am obviously missing something but I don’t understand as I’ve tried reversing the LED polarity with still the same result. Works in conventional but no dice in command.

Both diodes have to match. I'm hoping you meant swap the input.

@Vernon Barry posted:

Both diodes have to match. I'm hoping you meant swap the input.

Vernon, they are pointing the same way! The wire goes around a corner.

However, I now see the problem!  They're both pointing the same way, but they're pointing the wrong way!  Ground is positive for lighting in command mode!

Not this

VS this swap-corrected polarity

Again, I said swap the LED polarity to correct, not knowing and no previous indications of what else was in the circuit. Once we got the ENTIRE circuit- then the picture becomes clearer.

My bad in the schematic I had to start writing things down to make sure I didn’t do the same thing twice 😅 this is the correct way it’s wired

so out of curiosity I put a incandescent bulb on it and it does the same thing. Works in conventional but nothing in command.

I did replace the TRIAC as the old wiring was pinched and that TRIAC was shorted. I used THIS TRIAC.

any chance that I used the wrong TRIAC or something else on the R4LC crapped

Did you se the correct feature code (when setting TMCC ID) and also in command- hit AUX2 to toggle all light outputs on and off and back on?

Yup but can’t hurt to try again

Are the TRIACs the same for the different versions of the R2LC or R4LC?

If it works in conventional and not in command with an incandescent bulb, then we're not looking at LED wiring.  The only thing that comes to mind is a bad R4LC at this point or the R4LC configuration being incorrect.  Did you use AUX1 / "1" as the configuration code, that's early Legacy steam.

Also, change the cap to a .01uf, the .1uf is overkill.

Here's the programming instructions for the 6-11117 locomotive.

@DaveGG posted:

Are the TRIACs the same for the different versions of the R2LC or R4LC?

Same triacs for R2LC and R4LC.  They've changed the part number over the years, but the same series and all of them work the same way.  I use the MAC228A8G in everything from early R2LC's to the latest R4LC's.  They also work in the Legacy RCDR.

After a pause I was able to reprogram the R4LC and confirm correct operation with a standard bulb and my LED also now works. Thanks guys, sounds like my original issue was trying to remember the bias of the R4LC output 🤦🏻‍♂️

Conventional mode full wave track power on the lighting outputs.  Command mode, half-wave track power on the lighting outputs, frame ground is positive in command mode.  The R2LC-C07 is the only exception, in command mode frame ground is negative for the lighting outputs.