The 2SC3996 is covered by this 91.9 KB PDF, sorted under schematics although a name consisting only of a part code usually means a datasheet. In the Japanese JIS system, 2SC designates an NPN bipolar transistor. Package and manufacturer are not given. Use the sheet to check pin order, maximum voltage, current and dissipation, and to evaluate substitutes when the original part is hard to find. It opens in any PDF viewer. Always match the number printed on the component before replacing it.
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.