: 19V stops right at the first or second MOSFET. The laptop behaves as if it has no battery or charger connected.
Sometimes these boards are referred to by the laptop model (e.g., ) or the Compal internal name ( BSL50/BSL52 power rail diagram for this motherboard? La E801p | PDF - Scribd
Locate the DC-in jack interface page on the schematic. Trace the voltage through the first and second input isolation MOSFETs. If the voltage drops to 0V after the first MOSFET, look at the charging IC circuit (often an ISL or BQ-series chip) to verify if the ACIN signal is pulling high and driving the gates. Step 2: Test the "Always-On" Power Supply ( +3VALW / +5VALW )