[Richard]

Yep, I tend to agree with your conclusion that the Yamaha has a problem. I have exactly the same unit.  If you buy a replacement, make sure it has a switched 110 outlet on the back. That outlet (the white plug in the picture) is what powers the relays to switch when the unit is turned on.   That is incorrect information and I apologize for posting bad info. The relays are powered by the dash unit. The switch outlet on the back merely powers a red light to tell you the unit is on.