The Acer Aspire 4736G, built on the Compal LA-4495P (KALH0) architecture, represents a classic era of Intel Core 2 Duo performance paired with dedicated NVIDIA graphics. For chip-level repair technicians, this board is a staple in the workshop, known for its robust power delivery system but also for specific aging-related failures in its filtering stages and standby circuits. Utilizing the Intel PM45/GM45 chipset and the ICH9M Southbridge, this platform follows strict Compal power sequencing that is essential to master for successful logic board recovery.
Board Architecture & Technical Specifications
| Feature | Specification |
|---|---|
| Motherboard Model / ODM Part Number | Compal LA-4495P (KALH0, KAL90, KALG0) |
| Target Laptop Series / Form Factor | Acer Aspire 4736, 4736G, 4736Z |
| Chipset / CPU Architecture | Intel Penryn (Core 2 Duo) + PM45/GM45 + ICH9M |
| Super I/O (EC/KBC) Controller | ENE KB926QF D3 |
| Key Voltage Rails & Switching Coils | +3VALW (PL4), +5VALW (PL5), +1.5V DDR3 (PL6), +VCC_CORE (PL10, PL11) |
Real-World Motherboard Diagnostic Procedures
1) Input Power Stage & DC-IN Protection Circuit
On the LA-4495P, the primary power rail +19VB is managed by the ISL6251 (PU1) charging IC. If the laptop fails to power on and shows 0.00A on the DC Power Supply, begin by measuring the voltage at PQ1 and PQ2 (SI4407DY). Ensure the gate drive signal PACIN is present (approx. 3V) which enables PQ19 to pull the gates of the P-Channel MOSFETs low, allowing the adapter voltage to pass to B+. If ACIN (Pin 2 of PU1) is below 3.2V, the charging IC will not release the gate control, often due to a shifted voltage divider at PR5 and PR6.
2) Standby Rail Generation & Resistance Norms
The 3.3V/5V Always-On rails are generated by PU4 (RT8206B). In cases of a "No Power" state where the power button has 3.3V but the laptop doesn't trigger, check PL4 (+3VALW) and PL5 (+5VALW) for shorts to ground. Normal resistance on PL4 should be >200 ohms; if it is below 10 ohms, the Southbridge (ICH9M) or the ENE KB926QF EC is likely internally shorted. Verify that EN_LDO (Pin 4) is receiving the enable signal and that the LDO output (Pin 7) is providing a steady 5V to power the EC's internal logic before the main buck converters start.
3) VCORE Stability & The NEC/TOKIN Failure
A notorious issue with the LA-4495P platform is random freezing or shutdown when the AC adapter is plugged in, or failing to boot into the OS despite having a display. This is almost exclusively caused by the degradation of the NEC/TOKIN (OE128 or OE907) proadlizer capacitor located on the bottom of the board directly under the CPU socket. This capacitor filters +VCC_CORE. Using an oscilloscope, you will see massive ripple on the VCORE rail. The professional fix involves removing the NEC/TOKIN and replacing it with four 330uF Tantalum Polymer capacitors (low ESR) to restore rail stability and prevent CPU thermal/voltage tripping.
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
