Schematic for the Quanta N91A motherboard, revision 1A, with board number DAN91AMB6D0 stated in the name, in a 1.43 MB PDF. Quanta part numbers starting with DA and ending in a revision code identify the bare PCB, and this number is usually printed on the board itself. The diagram helps with tracing power rails, locating the charger and VRM circuits and finding test points when a board will not power on. Match the full board number and revision on the PCB before relying on component values. This appears to be one of several copies.
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 @abgm_manutencao_esquemas. 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.