The SY8208B (or similar Richtek/Silergy chips) responsible for generating +3VALW and +5VALW frequently fail or burn out due to liquid damage near the keyboard or trackpad connectors. Step-by-Step Troubleshooting Using the Patched Boardview
The LAC701P Rev 10 is an 8-layer board (Top, Inner1, GND, Power1, Power2, Inner2, Inner3, Bottom). The original boardview often misplaces vias on inner layers, showing a trace connecting to Layer 3 when it actually routes through Layer 5. This leads to wasted time probing non-existent connections.
If you work on Lenovo Legion or IdeaPad Gaming 3 motherboards, do not settle for the broken OEM boardview. Seek out the patched version. Verify its fixes. And if you discover new errors, contribute your own patch back to the community. That is how the entire repair ecosystem evolves. lac701p rev 10 boardview patched
Always cross-reference your patched boardview with the official LA-C701P schematic diagram. While the boardview tells you where a component is, the schematic tells you what value it should be (e.g., a 10uF 25V capacitor versus a 0-ohm resistor). Never inject voltage into a circuit without using the boardview to confirm that the rail you are powering cannot tolerate higher voltages, especially near the CPU or RAM core lines.
Use a voltage injection method (e.g., inject 1V to 2V at 2A into the rail) and look for the component that gets hot using freeze spray or a thermal camera. Step 2: Check the Power-On Sequence via the Super I/O (EC) If the laptop has no power but no short is present: Locate the chip on your patched boardview. This leads to wasted time probing non-existent connections
– A technician uses a multimeter in continuity mode to map out 50–100 unknown connections, then updates the netlist.
Standard multi-stage step-down system (19V primary input to 5V, 3.3V, 1.05V, and RAM/CPU core VCC). Verify its fixes
For more advanced diagnostics, OpenBoardView provides a network tracking feature that highlights all components connected to a selected net. This allows technicians to trace signal paths visually and identify all points that should share the same electrical connection. If you suspect a broken trace or open circuit, this visualization helps you locate every point where the signal should be present.