Schematic PDF, 1.56 MB, whose name points to the U99 and U93 models, likely variants sharing one design. No board number, revision or brand appears in the name, so confirm compatibility from the title block inside. A schematic like this shows power rails, regulator circuits, the charger stage and signal routing between the main chips. Use it to identify expected voltages and component values while repairing. Check that the board markings match before trusting 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 @cyberlanelectonik. 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.