LCRU 2 modification to drive ERR sound commander

Again, given that I had 3 different LCRU 2 boards on the bench, 1 was in the AEC switcher, the other 2 were straight from Lionel Parts I bought (because they happened to be the cheapest ones) 691PCB1001 but all 3 used the exact same 10K resistor for R33. I modified all 3 boards and tested them. I also didn't mention, I also used a brand new ERR Railsounds commander http://www.3rdrail.com/err-3rd...lSoundCommander.html and it too was not driven properly by the factory LCRU 2 and the 10K resistor. Just sharing, this wasn't a one off test, this was pretty much a smoking gun that if you have or consider using an LCRU 2 (and why not mod that old engine and add TMCC?) well, to get sounds working, this is a pretty sure bet mod.

Also, while on the topic to consolidate mods- Taken from here https://ogrforum.ogaugerr.com/...ector-pinout-diagram

gunrunnerjohn posted:

The LCRU has a positive output from the lighting triac.  It will require a .01uf capacitor across the light output to trigger the triac using just an LED.

 That explains why I was frustrated with my LED headlight mod not lighting, so when I started probing and the extra capacitance from my body (finger) touching the positive lead of the LED it flickered and came on as long as I was touching.

Good info, thanks! Also … very brave, experimenting with new boards! Did you buy them last November by any chance?

Yes, I bought them in November, but no, it was after the sale. Sadly, I was knee deep in my learning of lionel parts and systems used and was completely unaware of what the LCRU2 was at the time. I did place and got a good order in during the sale, but didn't prep or know enough in advance to know all the boards I wanted to play with.  Oh well, $50 isn't too bad for what this board does and is. Perfect for slapping in that old 20XX series tender and loco to give you TMCC. My particular project is a 2035, but looking for other fun locos that are not of great collectors status, but good runners and worthy of spending a few $ on.

Makes perfect sense, the sound boards have an opto-isolator on the input serial data, and a 10k resistor doesn't provide enough current to drive it.  Good to know, I confess to having never tried this, but I'll remember this if I decide I want to.  Of course, my go-to solution is always not to modify the factory board if possible, so I'd probably use the serial data buffer.  It would work the same with the LCRU2, just have to find the 5V source to power it.