Schematic labelled SENUSA 3, a 5.87 MB PDF, apparently a later version of the SENUSA design that also appears as revision 2. The name does not state the manufacturer or what device it belongs to, so check the title block on the first pages. A schematic like this is used to follow power rails and signals, find component values and plan measurements during diagnosis. Since component placement and values can change between revisions, confirm the board revision marked on the PCB matches this version.
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 @pdf_servicemanual. 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.