Power-supply service schematic for the Audio Pro AP3000, based on the pwr and sm tags in the name. The 921 KB PDF should show the mains input, transformer, rectifier, filtering and regulated rails that feed the rest of the unit. Technicians use it to find blown fuses, shorted rectifiers, failed regulators or dried capacitors, comparing measured voltages with the values marked on the sheet. Check the board revision against the drawing and observe mains safety, especially around the primary side and reservoir capacitors.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @pdf_servicemanual. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.