|best| - La-e791p Rev 2.0 Schematic Diagram

The Compal LA-E791P Rev 2.0 (also known as CSL50/CSL52) is a motherboard schematic used primarily in HP 250 G6 and HP 15-BS series laptops. This document is an essential technical blueprint for hardware repair, detailing the power sequences, component layouts, and signal paths of the device. Technical Summary

The motherboard is designed by Compal Electronics and supports the following core hardware configurations:

Processor (CPU): Intel Sky Lake-U or Kaby Lake-U series processors.

Graphics (GPU): Integrated Intel HD Graphics or dedicated AMD Radeon R17M with DDR3L VRAM. Memory: Dual-channel DDR4 SO-DIMM slots.

Storage Interfaces: Supports both SATA (HDD/SSD) and PCIe (M.2 NVMe) interfaces.

Power Management: Utilizes a multi-rail system, including critical power states like +VCC_CORE, +3VALW, and +5VALW. Key Schematic Sections

Block Diagram: An overview of how the CPU, PCH (Platform Controller Hub), and GPU interact with peripheral ports like USB, HDMI, and LAN. La-e791p Rev 2.0 Schematic Diagram

Power Delivery Network (PDN): Detailed diagrams of voltage regulators (Buck converters) that step down the 19V adapter input to lower voltages like 1.2V (RAM) or 1.0V (CPU).

Signal Integrity: Pin-out definitions for the LVDS/EDP display connector, keyboard interface, and BIOS/EC (Embedded Controller) chips.

Security Notice: The document is marked as proprietary and confidential by Compal Electronics, containing trade secrets intended only for authorized service providers. Resources for Repair

If you are troubleshooting a "No Power" or "No Display" issue, these community-vetted resources can provide the specific Rev 2.0 files or guidance:

Downloads: Schematic and Boardview files are often hosted on enthusiast sites like GeekDais or The Tech Stall.

Troubleshooting Guides: Video walkthroughs on diagnosing specific rails like +VCC_CORE can be found on YouTube. The Compal LA-E791P Rev 2

Community Support: Detailed discussions regarding BIOS dumps and power issues for this specific revision are active on the VLab forums. CSL50 LA-E791P Rev 2.0 Schematic | PDF - Scribd

4. How to Use the Schematic for Troubleshooting

Here is a practical workflow for a "Dead Laptop" using this schematic:

Step 1: Visual Inspection

Look for physical damage. If you find a burnt component, search its reference designator (e.g., "R450") in the schematic PDF to find its value.

Step 2: Check Power Rails (Shorts)

Measure the main coils (Inductors) for a short to ground using a multimeter in diode mode.
Common Coils:
- Coil 3V/5V: If shorted, the laptop consumes high current and gets hot.
- Coil 1.05V: Often shorted on these boards due to CPU PCH issues or bad capacitors.

Step 3: Follow the Signals

If there are no shorts but the laptop is dead, open the schematic to the Power Sequence page.
Check voltages in order:
1. ALW (Always On) 3.3V: Powers the EC.
2. ACIN: Does the EC know the charger is plugged in?
3. LID_SW#: Is the lid switch stuck closed?
4. RSMRST#: Resume Reset signal.

Common Faults Diagnosed via the LA-E791P Rev 2.0 Schematic

Based on real-world repair logs, here are three frequent failures unique to this revision. Look for physical damage

1. What is the LA-E791P REV 2.0?

First, let’s decode the nomenclature. LA-E791P is the motherboard codename assigned by Quanta Computer, one of the largest Original Design Manufacturers (ODMs) in the world.

Manufacturer: Quanta (Often labeled with a "Q" logo or part number).
Model: LA-E791P.
Revision: REV 2.0 (Crucial distinction; REV 1.0 and 3.0 have different component placements and routing).
Commonly Found In: Acer Predator Helios 300, Acer Nitro 5 (specific variants), and some HP Omen models. These are high-current, high-performance gaming laptops.

The board is typically paired with Intel 8th or 9th Gen H-series processors (Coffee Lake) and dedicated NVIDIA GeForce GTX 1060/1660 Ti or RTX 2060 graphics.

Practical Use Case: Tracing a "No Power" Condition

Using the schematic, a technician would:

Check +VIN at DC-in jack → Page 2.
Verify AC_IN# is low (active) → Page 3.
Measure +3.3V_ALW on inductor PL401 → Page 5.
Check EC_ON signal from EC → Page 18.
Confirm PCH_RSMRST# → Page 14.

Without the Rev 2.0 schematic, step 4’s voltage threshold (1.8V for enable vs 3.3V for logic) would be unknown—leading to misdiagnosis.

Mastering the LA-E791P REV 2.0: The Definitive Guide to the Schematic Diagram

In the world of modern laptop motherboard repair, boardview files and schematic diagrams are the holy grail. Without them, diagnosing a short circuit, a missing voltage rail, or a blown Integrated circuit (IC) is akin to performing surgery blindfolded. Among the myriad of motherboard models circulating in the repair community, one particular board has garnered significant attention due to its prevalence in high-performance laptops: The Quanta LA-E791P REV 2.0.

If you are searching for the LA-E791P Rev 2.0 Schematic Diagram, you are likely staring at a dead motherboard from an Acer Aspire or similar gaming series, trying to resurrect it. This article provides a deep dive into everything you need to know about this specific schematic—where to find it, how to read it, common failures, and how the diagram helps you fix them.

4. Embedded Controller (EC) and Super I/O Logic

The schematic details the EC (e.g., IT8226 or MEC1653) which handles:

Power button sequencing.
Lid switch and thermal trip.
Fan PWM control (dual zone).
Battery LED indicators.

Rev 2.0 enhancement: The EC’s +3.3V_RTC backup circuit now includes a larger supercapacitor (0.22F vs 0.1F in Rev 1.0), allowing RTC retention for up to 72 hours instead of 24.

7. Debug Flowchart (Schematic-Based)

Start: No power
    ↓
Measure +3VLP at JP1 pin 1 → No → Check DC-in circuit (page 5)
    ↓ Yes
Measure +3V_ALW → No → Check PU402, EN signal from SIO (page 28)
    ↓ Yes
Measure EC_PWRBTN# toggle when pressing power button → No → Replace SIO or check button (page 8)
    ↓ Yes
Check PM_PWRBTN# to CPU → No → Broken trace from SIO to CPU (page 26)
    ↓ Yes
Check VR_READY (should go high after Vcore) → No → Replace RT8239B or MOSFETs (page 30)
    ↓ Yes
Check ALL_SYS_PWRGD → No → Check +1.2V_DDR, +1.8VS, +0.675VS (page 15)
    ↓ Yes
Check SIO_PWRGD → No → SIO firmware corrupted → Reflash EC BIOS
    ↓ Yes
Display & boot

Fault 2: Lights up but No Display (External monitor works)

Diagnosis: LCD Backlight or LVDS/eDP circuit issue.
Schematic Fix: On page 20 (LCD Connector JLVDS1), check:
- Pin 1 (LCDVDD): 3.3V
- Pin 3 (LCD_BKLT_EN): 3.3V (Backlight enable)
- Pin 4 (LCD_BKLT_PWM): Dimming control.
- If BKLT_EN is missing, jump to the EC output pin in the schematic.