2SC3789 is the sole identifier on this 157 KB PDF, placed in the schematic section of the index. Japanese JIS numbering reserves the 2SC prefix for NPN bipolar transistors, so the file should describe a single semiconductor rather than a whole board. Manufacturer and package are not stated. Use it while diagnosing a failed stage: confirm which pin is the collector, look up maximum ratings and check gain when choosing a replacement. Always compare the code printed on the device with the document before ordering.
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.