The Compal LA-4201P (also known as the Cantiga platform) is a classic powerhouse from the Core 2 Duo era, frequently found in high-performance multimedia laptops like the Acer Aspire 6930G series. This board is architecturally significant due to its Intel GM45/PM45 Northbridge and ICH9-M Southbridge configuration, paired with an MXM 2.0 discrete graphics slot. For repair technicians, this board represents the pinnacle of modular laptop design, but it also presents specific challenges regarding the ENE KB926 Super I/O integration and the thermal management of the Cantiga chipset.
Board Architecture & Technical Specifications
| Feature | Specification / Component |
|---|---|
| Motherboard Model / ODM Part Number | Compal LA-4201P (JALB0) |
| Target Laptop Series / Form Factor | Acer Aspire 6930 / 6930G (16-inch Multimedia) |
| Chipset / CPU Architecture | Intel Penryn (Socket P) + GM45/PM45 + ICH9-M |
| Super I/O (EC/KBC) Controller | ENE KB926QF D3 |
| Key Voltage Rails & Switching Coils | +3VALW (PL4), +5VALW (PL5), +1.05VS (PL10), +VCC_CORE (PL11/PL12) |
Real-World Motherboard Diagnostic Procedures
1. Input Power Stage & DC-IN Protection Circuit
On the LA-4201P, the primary power rail +19VB is controlled by the charging IC ISL88731 (PU1). If the laptop won't turn on and has 0A draw, first check the voltage at the drain of the first MOSFET PQ1. If 19V is present at the drain but not the source, verify the ACIN signal on pin 13 of PU1 (should be ~3.2V). If ACIN is present but PACIN is low, the protection circuit is active. Common failure points include a leaky ceramic capacitor on the DCBATOUT rail or a high-resistance failure of the current sense resistor PR3 (0.01 Ohm). Ensure PQ1 and PQ2 (P-Channel MOSFETs) are getting the correct gate drive from the charging IC.
2. Standby & Secondary Rails Generation
The LA-4201P utilizes the ISL6236 (PU4) to generate the Always-On rails. Before pressing the power button, you must measure +3VALW at PL4 and +5VALW at PL5. If these are missing, check the LDO output on pin 7 (VREG3) and pin 17 (VREG5). A common issue on this board involves the +1.05VS rail (generated by PU10), which powers the Northbridge. If the laptop triggers but immediately shuts down, check the resistance to ground on PL10; a value lower than 10-15 Ohms might indicate a shorted Northbridge (GM45), which is a frequent failure point in this generation due to thermal stress.
3. Power-On Sequence & Signal State Tracking
The power-on sequence on Compal boards is strictly orchestrated by the ENE KB926. Upon pressing the power button, the EC sends ON/OFF# to the Southbridge. Monitor the RSMRST# (pin 100) signal; it must go high (3.3V) to signal the ICH9-M that the standby power is stable. Following this, the Southbridge should release PM_SLP_S3# and PM_SLP_S4#. If these signals are missing, check the 32.768kHz crystal (Y2) near the Southbridge. Furthermore, because this board uses an MXM2 slot, a failure in the discrete GPU card can pull down the SYSON or SUSP signals, preventing the secondary VS rails from appearing. Always test the board without the MXM card installed to isolate power rail issues.
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
