A 155 KB PDF bearing the part number 2SC4734 and nothing else. The 2SC prefix belongs to the JIS/JEITA system for NPN bipolar transistors, so despite the schematic label this is best treated as a component datasheet. Typical uses are confirming which leg is collector, base or emitter, reading absolute maximum ratings and gain figures, and finding a cross-reference when the original is unavailable. Match the package and marking on the board before trusting the pinout shown in the document.
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.