PDF file of 466 KB covering the 2SC5090 part, a JIS-registered NPN bipolar transistor going by its 2SC prefix. It sits under the schematic type, but the name suggests a component datasheet rather than a board diagram, and no maker or package is mentioned. Open it in a standard PDF reader to look up pin order, absolute maximum ratings and gain classes. When diagnosing a failed stage, compare measured junction behaviour against the sheet and confirm the board marking matches before substituting.
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 @cyberlanelectonik. 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.