I have 2 AR-DV1's. A few days ago one showed the dreaded 'No Res' message, and after removing and replacing power it started OK, but had lost its settings. Ran for a few days.
Today it started to make a loud buzzing sound. I reset it but the noise continued.
I decided to swap power cables. The buzzing then started on the other AR-DV1.
It was the original AOR power supply 'dying'.
Both Radios are OK now.
So as obvious as it may sound. If your DV1 starts playing up, always try it with another power source first.