The 2SC4423 is described by this 102 KB PDF, which the index lists as a schematic. Since 2SC is the JIS prefix for NPN bipolar transistors, the contents should be a datasheet with absolute maximum ratings, electrical characteristics and mechanical outline. Use it to identify base, collector and emitter, to estimate whether a part has failed, and to compare substitutes. Any standard PDF reader will open it; confirm the marking and package of the actual transistor before making a swap.
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.