Turn off all power, set your multimeter to resistance mode (low ohms), and check all major coils (PL401, PL402, PL501, etc.) against ground. A reading close to 0 ohms on a non-CPU rail indicates a shorted component (usually a ceramic capacitor or high-side MOSFET).
I can give you step-by-step instructions for your specific repair scenario. Share public link
If these rails are missing, check if the chip is receiving its 19V operating power ( VIN ) and check the Linear Regulator outputs ( +3VLP / +5VLP ). Stage 3: Secondary and Run Rails
: Firmware files required to fix "no power" or "slow boot" issues, often needing a "Clean ME" (Management Engine) version for this specific board. Compal Power Supply Schematic | PDF - Scribd la-9413p rev 1.0 schematic
A schematic is difficult to use alone. You also need a (typically LA-9413P Rev 1.0.cad ). Boardview software (OpenBoardView, BoardViewer) lets you click on a component like "PC401" and see its physical location on the motherboard. Pairing the schematic (what the signal does) with a boardview (where the part is) is the ultimate repair toolkit.
[DC Jack / Battery] ──> +B (19.5V Main Rail) ──> +3VALW / +5VALW (Always-On Rails) │ [Power Button Pressed] <───────────────┘ │ ▼ [EC Drops PM_PWRBTN# to PCH] ──> PCH Wakes Up (S3/S0 States) │ ▼ [Run Rails Enable (+1.35V, +1.05V, CPU_CORE)] 1. The Main DC-In Rail ( +B )
Resistors, capacitors, ICs (chips), MOSFETs, diodes. Signals: Data paths, clock signals, enable signals. Voltages: Power rails, such as Why You Need the LA-9413P Schematic Turn off all power, set your multimeter to
The high-voltage 19V rail travels across the entire board to supply various buck converters. The small multi-layer ceramic capacitors (MLCCs) filtering this line frequently short internally.
The LA-9413P is a motherboard designed by Compal Electronics. The denotes the first revision of this board design. It is built to support Intel's Haswell-based processors and is frequently found in high-performance configurations of the Dell E6540. Platform: Compal LA-9413P Target Device: Dell Latitude E6540 Revision: 1.0
What are the ? (No power, no display, or shutting down?) Do you have a multimeter or DC power supply ? Have you checked for liquid damage ? Share public link Share public link If these rails are missing,
The main power bus derived from either the DC-in jack adapter ( +DC_IN ) or the battery pack ( +BATT ). It hovers around 19.5V from the adapter.
Present only on boards with discrete graphics, powering the dedicated GPU. 3. Using the Schematic for Common Failure Troubleshooting
These rails activate sequentially after the power button is pressed: