The chip frequently corrupts or fails entirely, preventing the laptop from triggering the power-on sequence.

: Highlights entire copper traces (nets) across multiple layers of the board.

: Locate PQ9 and PQ10 near the DC jack area to test for continuity to ground. 2. The 3V/5V Always-On Controller (PU5)

: Locate chip U14 (the ENE KB9012 Embedded Controller). Verify that it receives +3VACC power.

A classic Windows-based application that supports a wide variety of file formats, including .bdv and .bv . Common Repair Scenarios Using the LA-7912p Boardview

While a standard schematic shows you the theoretical electrical connections (how components talk to each other conceptually), a shows you the physical layout of the board.

He checked the resistance again. The meter jumped, then settled on a high number.

: Use your multimeter to probe pins 5–8 (Drain) of PQ10. You should read close to 19V. If you read 0V or a pulsing low voltage, a short circuit down the line is likely pulling the rail down. 2. Verify the 3.3V and 5V Always-On Rails

The isolation MOSFETs PQ9 and PQ10 are frequently cited as common failure points. If the laptop doesn't power on from the AC adapter but works from a charged battery, these MOSFETs are likely faulty. Symptoms can also include erratic charging behavior. In one detailed case study, replacing PQ9 (AO4466) and the charging controller PU4 (BQ25A) resolved a "no power" condition, though strange battery percentage cutoffs (power disconnecting at 98% charge) required further troubleshooting of the ACDET signal.

Open the boardview and search for the input mosfets: and PQ10 . Click on the pins of PQ9 to trace the VIN net.