The COMPAL LA-B161P (also known by its internal project name Z5WAH) is a staple of the Acer Aspire E5-511 and E5-511G series. Architecturally, this board represents the shift toward the Intel Bay Trail-M SoC (System on Chip) platform, where the CPU, PCH, and Graphics are integrated into a single BGA package. For repair technicians, this integration means that diagnostic accuracy is paramount, as a simple short on a secondary rail can often point to a non-replaceable (economically) SoC failure. This guide breaks down the power distribution and signal sequencing specific to the Compal design logic used in this board.
Board Architecture & Technical Specifications
| Specification | Component / Value |
|---|---|
| Motherboard Model / ODM Part Number | Compal LA-B161P Rev 1.0 (Z5WAH) |
| Target Laptop Series / Form Factor | Acer Aspire E5-511 / E5-511G (15.6") |
| Chipset / CPU Architecture | Intel Bay Trail-M (Celeron N2830 / Pentium N3530) |
| Super I/O (EC/KBC) Controller | ENE KB9012QF-A4 (Internal Flash 128KB) |
| Key Voltage Rails & Switching Coils | PL401 (+3VALW), PL402 (+5VALW), PL602 (+1.35V_DDR), PL701 (+VCC_CORE) |
Real-World Motherboard Diagnostic Procedures
1) Input Power Stage & DC-IN Protection Circuit
The LA-B161P utilizes the BQ24735RGRR (PU301) as its charging and power path controller. When the adapter is connected, the first check is the ACDET (Pin 6), which should be approximately 2.6V via the PR303/PR306 voltage divider. If ACDET is correct, the IC should output ~25V on ACDRV (Pin 4) to drive the gates of the two N-Channel isolation MOSFETs, PQ302 and PQ303. If you find 19V on the drain of PQ302 but 0V on the drain of PQ303, check for a short to ground on the +19VB rail (B+) at the current sense resistor PR302. A common failure point here is a ceramic decoupling capacitor shorting out under the SoC area.
2) Standby & Secondary Rails Generation
The Always-On rails (+3VALW and +5VALW) are managed by PU401 (RT8243AZQW).
- Check Pin 12 (VIN) for 19V and Pin 13 (EN) for the enable signal.
- Measure resistance to ground on PL401 and PL402. On the LA-B161P, a low resistance (below 100 ohms) on the +3VALW rail often indicates a punctured ENE KB9012 EC or, worse, a shorted SoC.
- If the LDO voltages (Pin 14 - +5V_LDO and Pin 15 - +3V_LDO) are present but the coils are not switching, verify the EC_ON signal from the KBC.
3) Power-On Sequence & Signal State Tracking
Since the LA-B161P uses the ENE KB9012, it requires firmware to operate. If the laptop is "dead" despite having 3.3V on the power button, the EC might be corrupted.
- Verify RSMRST# (Pin 100) goes high (3.3V) after the power button is pressed.
- The SoC must then release PM_SLP_S4# and PM_SLP_S3#. If these signals remain low, the SoC is not receiving its required clock (check 32.768kHz crystal Y2) or the BIOS/ME Region is corrupted.
- For this specific board, always ensure you use a "Clean ME" BIOS dump, as the Bay Trail platform is highly sensitive to TXE/ME region mismatches which cause 30-minute shutdown issues or no-display symptoms.
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
