Lae791p Rev 20 Schematic Better ((better)) -

Before you plug in your soldering iron, verify your schematic source. If the diagram does not include color coding, explicit component ratings, and operating voltages, keep searching. The extra 20 minutes spent finding a better Rev 20 schematic will save you two hours of troubleshooting and prevent you from blowing a new IC.

: The board heavily relies on specific chips. Common troubleshooting points include:

: Revised decoupling capacitor arrays reduce ripple voltage on core logic rails.

In Revision 1.0 diagrams, certain resistor values and capacitor tolerances are marked as "Open" (unpopulated) or feature placeholder values. Revision 2.0 reflects the exact hardware configurations found inside the retail units of the HP 250 G6 and 15-BS series. This eliminates guesswork when replacing burned-out SMD components. 2. Corrected Power Sequencing Diagrams lae791p rev 20 schematic better

| Symptom | Likely Fault Area | How the Schematic Helps | | :--- | :--- | :--- | | | DC power input, main power rails, or charging IC (BQ25A). | Trace voltage from the power jack through the charging circuit. Identify power sequencing. | | Black Screen / No Display | Failed BIOS update or corrupted BIOS. Bad signal from EC_RSMRST#. GPU solder issues. | Find the BIOS chip location and pinout. Trace the EC_RSMRST# signal to find the root cause of the failure to start. | | Fan Not Spinning | The fan connector's pinout is unknown, making it hard to probe. | Discover which pin provides power, ground, and the PWM speed control signal to test them properly. | | No POST | Failure in a critical power rail (e.g., GPU power) causing a short to ground. | Identify test points and components responsible for specific voltages, such as PJV1 for the GPU. | | Intermittent Charging | The battery management system is misbehaving. | Understand the communication lines between the battery, the EC, and the BQ25A charging IC. |

: The laptop turns on and displays an image on external monitors, but the built-in screen remains pitch-black.

It looks like you’re referring to a specific document or schematic revision: . Before you plug in your soldering iron, verify

: Locate the PWM IC responsible for the 3V and 5V rails. The schematic will help you check the Enable (EN) signals and Power Good (PG) pins to see if the IC is faulty or being shut down by a downstream short. Black Screen (No Display) : Fault : Fan spins, but there is no image on the LCD.

Always-on voltage rail powering the EC and power button logic.

Working on modern multi-layer PCBs like the LA-E791P requires the right tools and techniques to avoid accidental damage: : The board heavily relies on specific chips

The LA-E791P (often prefixed with Compal , the original design manufacturer) is the main logic board for a wide range of HP laptops, primarily from the and 15-bs series . Other common model numbers that use this board include the HP 15g and 15-bs5xx series.

Missing VCORE is usually a broken PWM signal or a failed CPU-side MOSFET. 5. Embedded Controller (KBC/EC - NPC2151)