The Acer Aspire 5515 and eMachines E620 are built on the classic Compal LA-4661P (KAW60) motherboard architecture. This platform represents the late-2000s AMD Brazos/Athlon mobile era, featuring the RS780MC Northbridge and SB700 Southbridge. For chip-level technicians, this board is a prime example of Compal's logic design, utilizing a multi-stage power rail system that requires precise sequencing to initialize the AMD processor and integrated graphics.
Board Architecture & Technical Specifications
| Specification | Details |
|---|---|
| Motherboard Model / ODM Part Number | Compal LA-4661P KAW60 Rev 1.0 |
| Target Laptop Series / Form Factor | Acer Aspire 5515 / eMachines E620 (15.4" LCD) |
| Chipset / CPU Architecture | AMD Athlon 64 / Sempron (Socket S1) + RS780MC / SB700 |
| Super I/O (EC/KBC) Controller | ENE KB926QF-D3 |
| Key Voltage Rails & Switching Coils | +3VALW (PL4), +5VALW (PL5), +1.2VHT (PL8), +CPU_CORE (PL10/PL11) |
Real-World Motherboard Diagnostic Procedures
1) DC-IN Protection & Charging Stage Analysis
On the LA-4661P, the input power flows through the DC jack to the PQ1 and PQ2 P-Channel MOSFETs. These are controlled by the PU1 (ISL6251) charging IC. If the laptop has no power and no LEDs, first check for 19V at the drain of PQ2. If 19V is present at the source of PQ1 but not the drain of PQ2, inspect the PACIN signal. PU1 must detect a valid adapter voltage to pull the gates of PQ1/PQ2 low. A common failure point in this legacy board is the current sensing resistor PR3 (0.01 Ohm); if it drifts in value, the ISL6251 will trigger an overcurrent protection and shut down the main 19V rail (B+).
2) Standby Rail Generation & SB700 Resistance Checks
The +3VALW and +5VALW rails are generated by PU4 (TPS51125). This is an Always-On circuit. If the board fails to trigger, measure the resistance to ground on PL4 (+3VALW) and PL5 (+5VALW). In this AMD generation, a low resistance (below 50 Ohms) on the +3VALW rail often indicates a partially shorted SB700 Southbridge or a failed ENE KB926 EC chip. Ensure the LDO voltages (VREG3/VREG5) are present on PU4 pins 8 and 17 before replacing the PWM controller. Without these, the power button signal will never be processed by the EC.
3) Power-On Sequence & AMD Platform Reset Issues
The power-on sequence follows the standard Compal logic: EC_ON enables the ALW rails, followed by the power button press sending ON/OFFBTN# to the EC. The EC then releases PBTN_OUT# to the Southbridge. A critical signal to check with an oscilloscope is RSMRST# (Resume Reset) on pin 100 of the EC; it must go high (3.3V) to signal the chipset that power is stable. If the laptop turns on but has no display (Black Screen), the RS780MC Northbridge is a frequent culprit due to thermal fatigue. Before reballing, verify that +VCCP on PL8 and +CPU_CORE on PL10/11 are reaching their target voltages (approx. 1.1V - 1.2V).
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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