K-Line Big Boy 4015S - Railsounds issues after Cruise Commander M upgrade

Look at the tether carefully, broken wires in the K-Line tether are a frequent cause of issues like this.  Also, the CC-M is tied into the serial data, if it's pushed it over the edge in capacity, that will affect the sound.  The incidents of "odd sounds" sounds like serial data.  OTOH, the skipping chuff sure looks like a chuff switch issue, but it could be a serial data issue as well.

If it's not a bad tether and you still get issues with the "odd sounds", consider adding the R2LC Serial Data Buffer.  This is something I developed to fix overloaded serial data from the R2LC.

Hey John, does CC-M send serial data to L2RC or vice-versa? What causes overloading of serial data from the R2LC in the first place?

I'll ohm out the tether wires and take a closer look at wiring in general inside the tender.

The only source of the serial data is the RxLC, everything else connected to the serial data is a user.  The overloads come when one or more devices puts too much of a load on the serial data.  In your case, I'm more suspecting an issue with the tether wiring.

When you're checking the wires, wiggle them right at the connector as you check continuity.  They frequently break right at the connector.

Continuity on the tether wiring seemed ok - I wiggled and flexed the connector while I was measuring each wire in the tether and didn't see any resistance changes for any of them.

I ran it around the track some more and noticed a few things, some of which I may have already mentioned:

• chuff isreally inconsistent, lots of big gaps with no chuff at all
• lots of spurious whistles (not triggered by CAB-2)
• long whistles triggered by CAB-2 would also trigger crewtalk
• volume seemed to change on its own occasionally

Does this all sound like serial overload due to the recent installation of CC-M and the additional connection to R2LC serial? If so, I'd like to try out one of those serial data buffers to see if it helps. Sounds like I'd want to connect the serial buffer output to the serial going out to the tender through the tether - what's the best way to do that?

I have a suggestion.  Unplug J4 on the CC-M to remove that serial data load.  Then run this in conventional mode with the transformer handles but the command base unplugged.  See if the sound is normal running that way.  If the sound is normal, then I'd say it's the serial data.  However, if the sound is still wonky, I'd suspect some other cause.

Great idea, John. I'm a little ashamed I didn't think of that.

Sounds worked great in conventional mode, so it must be the serial issue. I'll be reaching out to you via email about getting a couple of those serial buffer kits.

Thanks again for all your help!

It happens.