LA-C781P

The (Revision 1.0) is a motherboard schematic specifically for the HP 15-AF series notebooks, often paired with the ABL51 motherboard designation. This schematic is a vital resource for technicians diagnosing "dead" units or power-on failures. Technical Overview Platform: AMD Beema/Mullins APU platform. Key Components: CPU: Integrated AMD APU. RAM: Typically supports DDR3L memory modules.

Conclusion

often list Compal board files, though many require a subscription. Community Forums

Then the machine erased its own BIOS and died forever.

Common pin/functions (labels vary)

1. Visual inspection: look for bulging caps, burned parts, cracked PCB traces.
2. Check mains fuse and NTC; test continuity on primary bridge diodes.
3. Measure DC on bulk cap (should read ~320–400 V for 230 VAC).
4. Power with series lamp or current‑limited supply; observe if switching starts (oscilloscope on MOSFET drain or controller pin).
5. If no switching, measure Vcc to controller; if absent, inspect startup resistor/circuit and primary cap.
6. If switching but no output, probe secondary rectifiers and transformer continuity.
7. Replace suspect electrolytics and optocoupler/TL431 if feedback regulation is unstable.
8. After repairs, retest under load and verify regulation and ripple.