Lac781p Schematic Top !!install!! -

Diagnosing a "no power" or "no post" condition requires tracing the power rails sequentially. The LA-C781P uses an primary system rail generation approach common to Compal designs. Phase 1: Primary AC/DC and Battery Input (+B) The power sequence begins at the DC-IN jack.

Check the 19V rail, specifically the input MOSFETs and the bq25a charging IC. Measure voltage at the input of the board.

The +3VALW and +5VALW rails are generated to keep the board in a standby state, waiting for a power button trigger. lac781p schematic top

If the LA-C781P schematic is unavailable, or if you want to cross-reference information, consider these alternatives:

Pin capacitor for +3V_EC , Reset line ( WRST# ), and Crystal Oscillator clock output. The Charger IC Chip Designation: Typically an ISL88739 or BQ24735 . Diagnosing a "no power" or "no post" condition

Memory power rail and termination voltage.

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A: The DC Power Path. Check the BQ24725A pins (ACDET, ACDRV). Check the main MOSFETs for shorts to ground (continuity test). Check the always-on 3.3V and 5V rails. If these are present, check the EC's crystal oscillator for activity.

This section is the "heart" of the repair process. It details the generation and flow of all major voltages, starting from the main DC-in (19V) from the adapter to the final low-voltage core rails. Check the 19V rail, specifically the input MOSFETs

DDR3L / DDR4 (depending on the exact sub-revision variant)