Decrypted copy of the Sony MS01 and MS03 documentation for motherboard MBX-143, roughly 1.14 MB in RAR form. The decrypted tag implies the original schematic was protected and has been unlocked, so it should open in an ordinary PDF viewer without a password. Use it to trace power rails, inspect signal routing and find test points and components during repair. Since no revision is stated, compare the MBX-143 label and revision on your board with the title block inside the drawings.
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 @generalschematics. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.