Here is a 42.1 KB PDF on the 2SC3707 transistor, listed in the schematic category. The trailing E after the part number is not explained in the name and should be read only as an edition tag of the document. Under JIS numbering, 2SC devices are NPN bipolar transistors. Look here for pinout, voltage and current limits and package information when diagnosing a failed stage. Opening it in any PDF viewer is enough; confirm the part marking on the board matches before relying on these figures for a substitute.
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.