Schematic PDF of 3.33 MB titled VST59SP89, with no brand or device description in the name, so the exact equipment it covers is unclear from the label alone. Open it in any PDF viewer and check the title block for the board or chassis it belongs to. Compare part numbers and connector markings with your unit before relying on it, then use the diagram to follow supply rails, measure test points against expected voltages and isolate faulty components.
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 @datasheets1. 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.
Any PDF readerSumatraPDFFirefox / ChromeFlexBV (links PDF to boardview)