Series datasheet for the 6GBU family in a 111 KB PDF. GBU denotes a common single-in-line bridge rectifier package, so this document most likely lists the voltage grades of a 6 A class bridge. It is catalogued as a schematic but describes a component, not a board. Technicians use it to check pin order (AC, AC, plus, minus), current rating and surge capability when replacing a shorted input bridge in a power supply. Verify the full part marking and heatsink mounting before substitution.
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.