PDF amplifier circuit built around the Sanyo STK412-170 hybrid module, rated at 180 W in the name, which also marks it as OK, presumably a verified design. It shows how the IC is wired with its supply, bootstrap and output components, which helps when assembling a board or repairing amplifiers that use this module. Measure the supply rails against the values in the drawing and confirm the module suffix before replacing parts, as STK series variants differ in rating.
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.