ERR RailSounds in Lionel PA

All you need is the serial data and power for the ERR RS Commander.  I can't tell from the photo what TMCC package that has, what's the Lionel product number?

It's #2000. PN 6-18953. The serial data is the issue.

JP,

I have this PA as well.  It's a little convoluted but doable.

See this thread for full details on a resistor change needed to guarantee enough drive for the ERR Sound Commander to work properly in all conditions: https://ogrforum.com/...87#82382494787770987

From that link here's a picture of the bottom of a 610-8583-256 LCRU with the solder pad of the serial data output highlighted (thanks to JETGUY).  In the annotations in the photo you'll see a reference to the resistor change:

For your PA you'll have to check your specific LCRU (691-PCB1-018 for the Alco PA, from Lionel Service Supplement 40, pp. 11 to 15) to determine the precise pin for serial data output, and the location of the resistor.  Unfortunately I do not have a picture of the 691-PCB1-018 handy since they appear to be long unavailable online, and my PA is packed away so I can't take it apart at the moment to get a picture.

This will also take a little more work because the schematic for the PA in Supplement 40 does not clearly indicate specifically which is pin on the 691-PCB1-018 serial data out, either by label or wire color:

Comparing the traces on 610-8583-256 in the picture at the beginning above with those on the bottom of the 691-PCB1-018 in your PA should allow you to determine which is the serial out pin on the 691-PCB1-018 LCRU in your PA.

Good luck with it.  Let us know how it turns out.

Mike

Thanks Mike, that's very helpful!

John

Bummer, he beat me to it, and used the same diagram.   If you have any issues with the serial data, I have the cure.  This is a serial port buffer than insures the serial data has the drive and amplitude to drive the RS Commander input.

Thanks a lot for your efforts. If I understand it correctly, the buffer keeps me from having to mess with a resistor change. All I have to do is find the correct serial data connection.

Agreed.  I think I'd go with John's buffer, unless you enjoy removing and replacing little tiny parts.

The reason I use the buffer is that I've had the serial data (even when I can find it), be marginal for driving the RS board.  The buffer is a 2X amplifier as well as a low impedance drive, so it is able to produce a full 0/5V swing on the serial data, and thus there's no issue with signal amplitude.

I get the 5V from the R2LC, in this case, since you have the LCRU, the 5V should be on the LCRU connection for these wires, two are 5V, and two are the PWM motor drives.  You're catching me a bit early, I'm going to make PCB's for the serial buffer and have them available soon.

I'm not in a huge rush --- I've had this engine for several years. Is it possible to let me know when your buffers are ready? My email should be available by clicking on my user name.

JPThut

I'll post something in the forum when the boards are available.  I figure the first bunch I'll offer a kit of parts, as you can see, there aren't many parts, but it's nice to have them on a small PCB.  The PCB's are on order, but in order to keep the cost down, they're coming by slow boat from China, so it'll be about 3-4 weeks before they're in.  I plan on having all the parts assembled at that time to package them up.

The board is .4" x .7" and you'll be able to just slip it into some heatshrink and wire it up.

Sounds good. I just took a look at my LCRU and if I get too antsy I may just replace the resistor. Having owned a DCC supply company and working with lots of DCC installations I'm not too afraid of small parts and "fine" soldering.

JPThut

If you're comfortable with chip resistors, it's no big deal.

John could I drive two DCDRs with one of these or would I need to put one of these on PWM forward and one on reverse ?          j

The DCDR doesn't take serial data, it takes the PWM outputs of the TMCC receiver.  Since they are driving an opto-isolator, they do present a significant load, so I don't know if two DCDR's will work paralleled, never tried it.

I had a chance to remove and get a good look at my PA's LCRU 691-PCB1-01B. It looks like things are arranged exactly like the one in the picture at the beginning of this thread. I included a picture.

Has anyone made any progress on any of this? JPThut, did you get the railsounds working? And if so, Gunrunnerjohn, are any of the serial buffer kits left? Not sure my eyes could handle swapping out the surface mount resistor.

Trying to figure out the pinout of the LCRU 691-PCB1-01B  (used an ATSF PA-1 as a "donor" when building my Baldwin DRX-6-4-2000) to see if it'll handle directional lighting and electrocouplers, as well as railsounds. Based on similar boards, it appears the pins are there, but whether they're functional, and provide the correct outputs is going to require a bit of testing.

Magicland,

Just as I was ready to solder to the two pins in the picture I found a B unit with RailSounds for a good price and bought it instead.