Manages battery charging and system power switching (e.g., BQ24780S). Power Rails: +VCC_CORE (CPU Voltage) +VGA_CORE (GPU Voltage) +1.2V_DDR (RAM Voltage) +3V / +5V (System Run Rails)
Open the PDF and search for “+3.3V_ALW” (always-on 3.3V). You’ll find that this rail comes from a voltage regulator (e.g., PU8 – RT8223P). ms-16j91 schematic
You can access these technical documents through specialized repair communities and databases: Manages battery charging and system power switching (e
The schematic will direct you to the first two N-channel MOSFETs. Set your multimeter to continuity mode and test for a short between the Source and Drain pins. If a MOSFET is shorted, it will beep and need replacement. In some cases, the gate voltage may be low (e.g., 9.7V instead of the expected higher voltage), indicating a problem with the charging controller. You can access these technical documents through specialized
A is arguably more useful than a schematic for physical repairs. While a schematic shows how things connect, a boardview shows where components are located on the physical PCB.