SC-2 erratic behavior

Try running an earth ground somewhere near it, it has an antenna for reception and may be having signal issues.

Will try it. Thanks for the quick reply.

John,

The earth ground did the trick.

Very much appreciate your help. 
Thanks again,

Mike

Great, I believe that's been mentioned before. 

The other thing to consider is the power supply to these should have the common to the TMCC/Legacy signal from the base, as they're just like a locomotive as far as TMCC is concerned.  If you power them from an aux supply, you should have the common connected to the common of the track supply.

I have had flawless operation if I connect the com terminal to the outside rail (U terminal of the transformer connected to the Legacy base) and also run a ground wire (third terminal on the plug of the legacy base wall wart or Pin #5 on the DB9 connector on the base) over the top of the SC-2 units.

I believe that's pretty much what I just recommended.

Yes you did. For some reason, sometimes it has to be said twice.

Thanks guys. The SC-2 appears to be working and responding perfectly now.

Always love a happy ending.

One of my SCIIs is behaving very erratically.  I have cut a grove in the case and attached about 6 inches of copper foil to the aluminum antenna strip.  The antenna is attached to the underside of the platform,parallel to the tracks. I already have a wire from earth ground wrapped around the SCII case.  my layout has a bare stranded common bus under the platform to which all common drops from rails are connected. The connection from the command base which is specified to be connected to the outside rail is connected to this bus as well.  I would like to try the wire from the transformer common ( actually the common bus) to the "common connector on the SCII, but I don't know where on the SCII this is located. What's the story guys?

   One other concern is that my 2 SCIIs and 1 SCI are mounted perpendicular to the layout platform. The other two work just fine. Is this orientation, perpendicular to the tracks and the command base a potential problem?

Orientation shouldn't be an issue.  The "common" connector on the SC2 aux power input would be the top wire toward the logo on the case.  Connecting that to track common may help.