The 2SD1937 transistor is the subject of this 42.0 KB PDF, whose name ends with an _E suffix that is not explained. In the JIS scheme the 2SD series consists of NPN transistors for low-frequency service, so the document is expected to be a component datasheet despite its schematic label. Technicians rely on such sheets to confirm pinout and maximum ratings and to pick an equivalent part. Opens in any PDF reader. Before relying on it, compare the package, marking and any hFE rank letter with the part on the board.
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.