The Unison Echo® Room Controller, both 4-Zone and 8-zone models, has a built-in power supply for EchoConnect station wiring and 24vdc Auxiliary power. The EchoConnect™ station wiring is polarity dependent, so the positive and negative should not be crossed. As a result, it’s important to verify the proper terminal on which to land the positive lead and negative lead.
There was a small change on the circuit board between Revision C and Revision D. You can find the circuit board revision on the small white sticker found at the bottom right corner of the circuit board. Revision C has the Station (+) terminal above the Station (-) terminal. It is labelled as such on the circuit board (see Figure 1). Revision D has reversed these so that the Station (+) terminal is now below the Station (-) terminal. The labelling on the Revision D circuit board reflects this change (see Figure 2).