A 54.5 KB PDF filed as a schematic and identified only by the short code 51HQ, with no brand, model or revision stated. The name resembles a family designation for a discrete power device, so the content is probably a series datasheet rather than a board diagram. Use it in any PDF viewer to look up pinout, package and maximum ratings when replacing a part. Because a series sheet can cover several voltage grades, match the full marking on your component to the correct variant 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.