Reference PDF of 194 KB for the 2SA1937, sorted under schematics in the index. Apart from the part code the name says nothing; the 2SA prefix follows JIS practice for PNP bipolar transistors, so treat the file as a datasheet. It will usually show lead assignment, package drawing, ratings and typical curves. Technicians use it to confirm pin positions on the board, interpret meter or tester readings out of circuit, and evaluate whether a substitute device matches the original specifications closely enough.
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.