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I have acquired a Lionel Alco PA that is equipped with TMCC and Signal Sounds. I believe it may have been the second A unit with the RailSounds in the other A unit or possibly the B unit of anmy PA                      ABA set. Be that as it may, I would like to install an ERR RailSounds in it. My problem is where to tap in to the serial data in the Lionel TMCC board. Has anyone done that or something similar? Any help would be appreciated.

JPThut

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  • Lionel PA
Original Post

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.ogaugerr.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:

Supplement 40, p. 11, Annotated [2020-06-28_16-32-53)

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

 

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  • Supplement 40, p. 11, Annotated (2020-06-28_16-32-53)

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.

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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.

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