Part reference for the 2sd1275, written in lower case in the name and stored as a 56.4 KB PDF under schematics. 2SD is the Japanese JIS prefix for NPN transistors intended for low-frequency circuits, so expect a datasheet rather than a circuit diagram. Typical content covers voltage and current limits, power dissipation, hFE classes and a pin diagram. Technicians consult it to test a suspect device, read its body marking correctly and select a compatible substitute with equal or better ratings.
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.