The 2SC3075 is covered by this 213 KB PDF, catalogued as a schematic but probably a manufacturer datasheet. The JIS prefix 2SC marks an NPN bipolar transistor designed for high-frequency circuits. Expect it to be used for identifying pins before desoldering and for reading breakdown voltage and collector current limits. It also helps when checking hFE ranges during a substitution. The name gives no package or maker, so confirm the code printed on the part before trusting the values.
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.