Hi,
Here’s the [https://elektrotanya.com/sony_dav-dz350_dav-dz650_dav-dz950_sm.pdf/download.html|service manual] for the player. Be patient as it takes a little while to go from ''processing'' to ''Download'', once you have passed the security check and clicked on Go to Download, ''below the Document preview box''.
Once you have downloaded the manual, go to p.34 to view the power board circuit and p.40 to view the block diagram for the power board control IC.
Hopefully this is of some help.