The Acer Aspire 5541G, built on the robust Compal LA-5911P (NAWA2) motherboard architecture, represents a classic era of AMD-based mobile computing. Featuring the AMD RS880M Northbridge and SB710 Southbridge paired with dedicated ATI Mobility Radeon graphics, this platform is a staple in repair shops. While durable, it is frequently sidelined by thermal-induced BGA failures and power rail degradation. As a senior engineer at geniusmind4u.blogspot.com, I have analyzed this board's power sequence to provide you with the definitive technical roadmap for restoration.
Board Architecture & Technical Specifications
| Component | Specification / Identifier |
|---|---|
| Motherboard Model / ODM | Compal LA-5911P (NAWA2) Rev: 1.0 |
| Chipset Architecture | AMD RS880M (NB) + SB710 (SB) |
| Super I/O (EC) | ENE KB926QF D3 |
| Charging Controller | Intersil ISL6251AHRZ (PU1) |
| System PWM (3V/5V) | TPS51125 (PU4) -> +3VALW / +5VALW |
| Main Voltage Rails | +19VB, +1.1V_NB, +1.2V_HT, +VCC_CORE |
Real-World Motherboard Diagnostic Procedures
1) DC-IN Isolation & ISL6251 Charging Analysis
On the LA-5911P, the 19V input (VIN) must pass through two P-channel MOSFETs (PQ1 and PQ2) to become the primary B+ rail (+19VB). If the laptop is dead with no lights, first probe PR3 (the main current sense resistor). If +19VB is missing, check the ISL6251 (PU1). Ensure DCIN (Pin 24) is receiving 19V and ACSET (Pin 2) is above 1.26V. If ACPRN# (Pin 23) is high, the IC is not detecting the adapter, preventing the EC from initializing the power-on sequence.
2) Standby Rail Generation & EC Wake-Up
The TPS51125 (PU4) is responsible for the Always-On rails. Before pressing the power button, you must measure 3.3V on PL4 (+3VALW) and 5.0V on PL5 (+5VALW). If these are missing, check the LDO outputs (Pin 8 for 3.3V and Pin 17 for 5V). A common failure point on this board is a short-circuit on the +3VALW rail caused by a degraded ENE KB926QF Super I/O chip. Verify that EC_ON is pulled high by the EC to enable the buck converters. If the EC does not have its 32.768kHz clock (Y3), the board will remain in a S5 state.
3) AMD Platform "No Display" & Reset Sequence
This generation of AMD boards is notorious for Northbridge (RS880M) failure. If the board powers on (fans spin) but provides no display, check the +1.1V_NB rail at PL10. Use an oscilloscope to verify LDT_RST# and PCI_RST#. If all voltages are present but there is no POST activity, the SB710 Southbridge or the RS880M Northbridge likely requires BGA reballing. Additionally, always perform a clean BIOS flash on U22 (2MB SPI Flash) using a verified dump before condemning the hardware, as the AMD SB710 often corrupts the firmware during thermal cycles.
Download Schematic & Boardview Files
Direct download link. Verified Compal LA-5911P technical 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
No comments:
Post a Comment