I have 2 belolab 8002. Years playing ok RCA connected. But now one BL8002 dows not go in to stand-by after i shut off the ampifier. Also after i disconnect the power for one night and disconnect signal cable, when i only connect the power cable red light goes on en after one second red turns into green amplfier stays on. When i connect RCA sound is fine. Bur after shut of the amplifier in not goes into Stand by. Anyone an idea, Which PCB or component could be defect?