A 2.19 MB RAR archive named MB39A132, which matches a Fujitsu (now Cypress) DC-DC converter or battery charger controller part number rather than a motherboard. The package probably holds the datasheet with pinout, block diagram, typical application circuit and electrical characteristics. Technicians use such a datasheet to check pin voltages, understand the enable and feedback logic and choose replacements when the controller fails. Confirm the exact marking and suffix on the chip before comparing pin functions, since related variants may differ.
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.