Lac781p Schematic — Top !exclusive!

: Powers the system RAM and the memory controller inside the AMD SoC.

This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. la-c781p не включается • Notebook1 форум

If 3.3V is present at the power button but the board doesn't react (no current draw change), the Super IO may not be sending the "S5_ON" or "RSMRST#" signals to wake the chipset.

| Power Stage | Description | Typical Components | | :--- | :--- | :--- | | | The 19V DC power from the laptop's charger enters the board here. | PJ1 (DC Jack Connector) | | Charging Circuit | Manages battery charging and routes power to the system. | PU1 (BQ24725A Charging IC) | | Main Power (B+) | The primary system voltage (often 19V) after the input MOSFETs. | PQ4 , PQ5 (Input MOSFETs) | | Always-On (ALW) | Low-voltage power (e.g., 3.3V, 5V) that is present whenever the AC adapter is plugged in, even when the laptop is off. It powers the EC/KBC and other standby circuits. | PU2 (Standby PWM IC - e.g., 8A 1L) | | BIOS/EC Power | Power supplied to the BIOS and Embedded Controller (EC) chip. | EC (ENE) chip, BIOS chip | | CPU/GPU Power (Vcore) | The regulated voltage that powers the CPU and GPU cores. | PL8 (Output Inductor) | | RAM Power | The regulated voltage for the system's RAM (DDR3). | Typically near the RAM slots. |

Once the main B+ voltage is stable, the schematic shows how it is stepped down by the "Shim" (PWM controller) to create the voltages (typically 3.3V and 5V). These are necessary for the Embedded Controller (EC) to wake up. lac781p schematic top

: Replace the BQ25A IC. Ensure no downstream short exists on the B+ rail before replacement. 2. Corrupt SPI BIOS or EC Firmware

In complex projects, a is the main sheet that ties together sub-circuits (power supply, preamp, output stage, protection). For a device containing an LAC781P, the top-level schematic would show:

For further reading, search for "L7812CV datasheet" and "linear power supply design tutorial."

Before diving into schematic tracing, verify the fundamental board infrastructure: Specification Details Compal LA-C781P (ABL51) Supported Devices HP Notebook 15-AF series (e.g., 15-af119ur, 15-af011ur) Processor Platform AMD Beema / Mullins SoC (e.g., AMD A6-6310, AMD A8-7410) System Memory DDR3L SO-DIMM (Low Voltage 1.35V) Charging IC Intersil ISL88731C or TI BQ24725A (labeled as BQ25A) Embedded Controller (EC) ENE KB9022Q Main SPI BIOS 8MB (64Mbit) Flash, e.g., Winbond W25Q64FVSIG Core Power Delivery Rails : Powers the system RAM and the memory

If your regulator circuit fails, the internal block diagram guides diagnostics:

To effectively trace a failure on the LA-C781P, technicians follow the power-up sequence chronologically. If the sequence breaks at any point, the component responsible for the next step is likely at fault.

: Use diagnostic tools before and after replacing components to ensure stability.

Based on repair logs and board inspection, the LA-C781P Rev: 1.0 features the following core hardware: If you share with third parties, their policies apply

: Generates the baseline voltages required for low-power operation and standby states. Outputs : +3VALW (3.3V Always-on via inductor) +5VALW (5.0V Always-on via inductor)

While the board layout (form factor) is identical across these variants, some peripheral components like the CPU, BIOS chip, and certain power delivery elements may differ. Always use a schematic that matches your processor variant where possible, or rely on the common power distribution networks.

This guide has transformed the seemingly obscure keyword "lac781p" into a defined, actionable repair manual for the LA-C781P (ABL51) motherboard. By understanding its identification markers, key components, and common failure modes, you are now equipped to approach repairs on this HP 15-af motherboard with confidence.