Specification sheet in PDF, around 82 KB, for the 2SD1781K NPN transistor of the JIS 2SD series; the K suffix denotes a specific version of the base part. Technicians consult it to read marking codes, lead assignment, voltage and current limits and hFE ranks for compact transistors used in switching and signal circuits. It helps confirm that a replacement has the same package footprint and electrical grade. Check the original component's code against the table before substituting 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.