A 103 KB PDF named only after the part 2SC3992, indexed as a schematic but in practice almost certainly a transistor datasheet. JIS numbering uses 2SC for NPN bipolar devices, so expect electrical characteristics, absolute maximum ratings and a package drawing inside. When a transistor in a power stage or driver circuit fails, this is the reference for pin order and voltage and current limits. Check the abbreviated marking C3992 on the actual component and compare packages before ordering a replacement.
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.