Schematic: La-c781p
| Component | Pin / Signal | Expected Voltage (DC) | Condition / Notes | | :--- | :--- | :--- | :--- | | | Main Power | 19V | Immediately after battery/charger connection | | Charger IC (PU1, BQ24725A) | Pin 20 (ACIN) | 19V | Adapter present | | | Pin 4 (ACDRV) | 25V | High voltage for turning on main input FETs | | | Pin 6 (ACDET) | 2.6V | Adapter detection voltage | | | Pin 16 (REGN) | 6V | Internal linear regulator output | | Always-On Regulators (PU2) | 3.3V rail (3V_ALW) | 3.3V | Always present when adapter is connected | | | 5V rail (5V_ALW) | 5V | Always present when adapter is connected | | Power Button | ON/OFFBTN# | 3.3V (drops to 0V when pressed) | Signal to EC to start the boot sequence | | CPU Regulator (RT8880C) | EN (Enable Pin) | 3.3V | Logic High to enable CPU Vcore generation | | | PVCC | 5V | Supply voltage for the IC | | | VCC | 5V | Core supply for internal logic | | GPU Regulator (ISL62883C) | VDD | 5V | Supply voltage | | | VIN | 19V | Main power input from B+ line | | EC (KB9022) | EC_ACIN | 3.2V | AC adapter present signal from charger IC | | | EC_ON | 3.2V | EC enabled signal | | | SUSP# | 3.2V | Sleep signal, low in sleep, high when awake | | BIOS Flash (U2) | Pin 1 | 3.3V | Chip Select, active low | | | Pin 8 | 3.3V | Power supply for the BIOS chip | | PCIe Slot | Reset (PERST#) | 3.3V | Present and stable after system reset |
"Always-on" rails required for the Super I/O and BIOS. +1.35V: Dedicated power for the DDR3L memory modules. +1.05V_VCCST: Sustained voltage for the CPU. +VCC_CORE: The main power supply for the processor.
When the system transitions fully to the "On" state (S0), the final high-current rails fire up. La-c781p Schematic
This is a major hurdle for any technician, but don't lose hope. The repair community has found creative and effective workarounds.
Connect your oscilloscope or multimeter to each large power coil on the board. Press the power button and look for a momentary pulse of voltage. | Component | Pin / Signal | Expected
The motherboard is commonly found in laptop models like the HP 15-af011ur . This board is designed for AMD-based systems, specifically utilizing the AMD Stoney Ridge or similar APU architectures. Core Components & Specifications
This is another classic symptom. The fan spins up to full speed immediately, but the screen remains black. +VCC_CORE: The main power supply for the processor
When you open the schematic, the diagnostic process relies on following the power-up sequence. Based on professional repair logs for this specific motherboard, the power rails and signals flow in this order:
By mastering the LA-C781P schematic, you elevate your laptop repair skills from component swapping to true logic-level diagnostics. Now go fix that dead Precision workstation!
: DDR3L (1.35V) or DDR4 (depending on the specific revision generation)
Q: What is the input voltage range for the La-c781p schematic? A: The input voltage range for the La-c781p schematic is typically between 2.5V and 10V.