A 196 KB PDF named for the 2SC4684 and listed in the schematic category. Its 2SC prefix is the JIS marker for NPN bipolar transistors, so the document is best read as a component datasheet. Beyond the part number, the name gives no information. Technicians refer to such sheets to confirm collector, base and emitter pins, look up voltage and current ceilings, and compare substitutes; also verify the actual marking on the device, as similar numbers are easy to confuse.
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.