The "top" of a multi-page schematic, sometimes called the cover page or block diagram, provides a system-level overview of the entire motherboard. It acts as a roadmap for the rest of the document. For a complex board like the LA-M402P , this top page is invaluable for understanding the big picture before diving into specific circuits.
Do you see any signs of near the USB-C ports?
: Small black parts (PR) near the BIOS chip or I/O controller, often caused by liquid spills. lad402p schematic top
Before diving into deeper searches, always double-check the original marking on the physical component, the PCB silkscreen, or the document you are referencing. A single character difference can completely change the result.
The schematic helps you diagnose these by following a structured process: The "top" of a multi-page schematic, sometimes called
Measure +DC_IN at the first leg of PQ1 . You should see 19.5V.
No. The physical topology is fixed. The top schematic shows a dedicated mechanical NC path. Changing it externally defeats safety ratings. Do you see any signs of near the USB-C ports
If you are currently diagnosing a specific board, let me know:
[ Power Input ] ---> [ TVS Protection ] ---> [ Bulk Capacitors ] | v [ Output Connector ] <--- [ LC Filter ] <--- [ Buck Switcher / Inductor ]
NC-1: Terminal 21 ----/ (open) ---- Terminal 22 NC-2: Terminal 31 ----/ (open) ---- Terminal 32