The power amplifier has stopped outputting sound. all other aspects (front end; WiFi, etc. are still working.  Inside on the main card I found the main amp power supply is supposed to be 36v. In my case it is only 17v. All low volt supplies are present and correct. Has anyone else experienced low supply volts and what did they do to fix it. Can’t find any broken diodes on the board. Does anyone have a circuit diagram??

BR Pete D.