The Acer Aspire E5-572, built on the Compal Z5WAW LA-B702P motherboard architecture, represents one of the final iterations of the high-performance Intel Haswell/Broadwell-M platform. Unlike its thinner 'U-series' counterparts, the LA-B702P often features a socketed or high-TDP processor and dedicated NVIDIA graphics (N15S-GT/N15V-GM), requiring a robust power delivery system. For chip-level technicians, this board is a classic Compal design, utilizing the ENE KB9012 programmable EC and a multi-rail standby system that is prone to specific sequence failures.
Board Architecture & Technical Specifications
| Specification | Details |
|---|---|
| Motherboard Model / ODM Part Number | Compal Z5WAW LA-B702P Revision 1.0 |
| Target Laptop Series / Form Factor | Acer Aspire E5-572 / E5-572G (15.6") |
| Chipset / CPU Architecture | Intel Haswell (4th Gen) + HM86/HM87 PCH |
| Super I/O (EC/KBC) Controller | ENE KB9012QF-A4 (Internal Flash) |
| Key Voltage Rails & Switching Coils | +19VB, +3VALW (PL402), +5VALW (PL403), +1.35V_DDR3L (PL501) |
Real-World Motherboard Diagnostic Procedures
1) DC-IN Protection & Charging Circuit Analysis
On the LA-B702P, the input stage relies on the TI BQ24735 (PU301) charging IC. If the laptop is dead with 19V present at the DC jack but 0V at the main rail (B+), check the gate voltage of the two P-Channel entry MOSFETs (PQ301 & PQ302). For these to conduct, the BQ24735 must output ~25V on ACDRV (Pin 4). If ACDRV is 0V, verify ACDET (Pin 6) is approximately 2.6V via the PR303/PR307 resistor divider. A common fault involves a shorted ceramic capacitor on the +19VB line, causing the IC to enter protection mode and shut down the input gates.
2) Standby Rail Logic & Resistance Norms
This board uses independent PWM controllers for the Always-On rails: PU401 (SY8208B) for +3VALW and PU402 (SY8208C) for +5VALW. Before replacing ICs, measure the resistance to ground on PL402 and PL403. A low resistance (<50 ohms) on PL402 usually indicates a punctured PCH or a shorted ENE KB9012 EC chip. If the rails are missing but no short is found, ensure EN (Enable) signals from the charging IC or the EC are reaching the chips. Note that +3VALW is required to power the EC's internal flash before the power button can even be sensed.
3) Power-On Sequence & Signal State Tracking
When the power button is pressed, the EC (KB9012) pulls KBC_PWRBTN# low and then sends PCH_PWRBTN# to the PCH. To diagnose a "trigger but no display" or "no trigger" scenario, use an oscilloscope to check the 32.768kHz crystal (Y2) and the SPI communication on the BIOS chip (U22). Crucially, the LA-B702P requires the RSMRST# (Resume Reset) signal to be 3.3V before the PCH will release the PM_SLP_S3# and PM_SLP_S4# sleep signals. If the board spins the fan for 3 seconds and dies, it is often an Intel ME (Management Engine) corruption in the BIOS or a failure of the +VCC_CORE rail (PU1101) to signal VR_READY.
Download Schematic & Boardview Files
Direct download link. Verified schematic / boardview archive.
Professional Repair Assistance
Explore our technician resources:
- 🛠️ Diagnose No-Power & Short-Circuit faults step-by-step: Interactive Laptop Diagnostic Lab
- 🛒 Original Replacement Motherboards & IC Components: Official Spare Parts Mega Store
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