My trigger wire is hooked up from the 990 to the 7500...both units are powered (physically switched off) off (I would assume this is standby mode-both units power plugs are plugged into surge protector...both lights on units are orange; (1)I turn the 990 on with my remote, (2) the 990 powers on, blue light comes on, relay clicks, 1-4 seconds later, 7500 relay clicks, blue light comes on...

When I shut 990 off with remote, both units go into standby....orange lights on...

That's the way it works on my units....