ELK-120 Setup Question

[tonti]

Final Question - 
I followed your advice and wired in another M1XOVR in the garage to drive outputs. From a system perspective I am all good. I tried it by driving a little piezzo as a beeper for the shop area. I also tested the Elk-120 and all works there too. Except when driving the Elk-120 from the M1XOVR i do not have control. 
 
I assume I need a negative return line (see dotted line in the picture) to the M1XOVR. Can you please confirm? 

 

[RAL]

I assume I need a negative return line (see dotted line in the picture) to the M1XOVR. Can you please confirm? 

 
Yes, you need the NEG connection between the 120 and the M1OVR to make this work.
 
A voltage always has a value, such as 0V or 12V relative to some reference point.  The outputs of the M1OVR are relative to its negative terminal.  But in order for the 120 to see that output as being 0V or 12V, it needs to share that reference, and that's why you must connect them together.
 
One thing you should not do is connect the +12V wires together from different power supplies.  They need to be kept separate.

 

[tonti]

Works well! Thanks a bunch!