Small 551 KB PDF schematic whose name holds only the token SY3, with no brand, model or revision stated, so the exact device cannot be confirmed from the name alone. Open the first pages to read the title block, which normally identifies the project and board revision. Schematics like this are used for tracing rails, following signals and locating components around a fault. Verify the board code printed on the PCB matches the code in the document before using any part values or measurement points from it.
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 @smschematics. 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.