Recently purchased 1989 CVP-50 played fine for several days after being brought home, then stopped producing any audio, niether in response to piano keys, accompaniment, nor rhythm selections. Speakers now only produce barely audible white noise whose level is unaffected by volume slide control. White noise cuts out when headphones are jacked-in but is not reproduced on headphones. Headphones do produce loud pops coinciding to relays on audio board kicking in and out on power-up and power-down. Hooked up RCA audio output jacks at piano rear to aux input of Bose speaker and got no sound. I suspect a fault in the amplifier assembly, either in the audio board (Syntaur Item 6560) or the power supply/amp (Syntaur Item 6561). These Items appear to be identical parts from a CVP-20 currently in Syntaur’s inventory, judging by comparison to the these photos from my CVP-50: https://photos.app.goo.gl/uGsZQ9uMWzgvm8RC6
Seeking feedback from the Synth repair forum regarding a recommended course of action. Are the symptoms I describe consistent with a failure in the amp? Are there any simple tests I can do with a multimeter to confirm my amp is bad before commiting to buying a replacement? I’d appreciate any advice you can offer.