At only 23.6 KB, this PDF named 30WQ04FX is probably a brief datasheet or ordering note for a discrete rectifier, despite being indexed as a schematic. The FX ending differs from the FN and F variants elsewhere in this index, which usually indicates a package or packing variation. Open it in any PDF reader to confirm ratings and outline before replacing a component on a power board. Double-check the full marking on the part, as the suffix can change the footprint even when the electrical rating is the same.
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.