Find the first two entry N-channel MOSFETs (often labeled PQ101 and PQ102 or similar depending on the Compal revision revision). Check if 19V passes through both. If 19V stops at the first drain, check the gate voltage driven by the Charging IC (commonly a BQ-series chip like BQ24735 ). If the gate voltage is not roughly 24V (for an N-channel loop), the charger IC is protecting the board from a downstream short.
Complete Guide to the Compal LA-C781P Motherboard Schematic: Repair and Troubleshooting
The is a vital blueprint for electronics engineers and component-level repair technicians. This specific motherboard layout—often designated as ABL51—is commonly used in Lenovo Ideapad laptops (such as the Ideapad 300 series).
The La-C781P is a power amplifier IC designed for use in audio equipment. The schematic diagram for this IC provides a visual representation of the internal circuitry, allowing engineers and technicians to understand the component's functionality and troubleshoot issues.
Dual-channel DDR3L or DDR4 (depending on the specific revision). La-c781p Schematic
The laboratory power supply immediately hits its current limit, or the charging adapter's LED blinks and goes out.
Here is where the LA-C781P saves your sanity.
: Always-on power required to run the Embedded Controller (EC) before pressing the power button.
Dedicated memory power rail for the DDR3L modules. Find the first two entry N-channel MOSFETs (often
Find the dual synchronous buck controller responsible for +3VALW and +5VALW .
This chart tells you the order in which voltages must turn on. If +3VALW is missing, +5VALW will never start.
A schematic is a detailed technical drawing that represents the electrical connections and components of a circuit board. For the LA-C781P, the schematic is typically a multi-page PDF document that includes various sections, each dedicated to a specific part of the motherboard's architecture.
You have a dead laptop. 19V is entering the board, but the fan doesn't spin. A generic multimeter check shows the 3.3V is present. Most people stop here and assume the BIOS is corrupt. If the gate voltage is not roughly 24V
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Look at the schematic for EN or ENTRIP signals. If the EC or PCH is pulling these enable lines to ground, the buck controller will remain asleep.
Locate the Always-On controller. Check for the presence of 3.3V and 5V linear regulator (LDO) outputs. These are required to wake up the Embedded Controller (EC) chip.