A healthy fuse will beep or register a near-zero resistance (under
Positioned directly in series with the main 24V power rail to catch overcurrent events early.
| Component | Value | Part Number / Notes | | :--- | :--- | :--- | | | 47µF / 63V | Electrolytic, Low ESR | | C2 (Input HF) | 0.1µF / 100V | Ceramic X7R | | IC | F4901 (or sub) | Actual chip (e.g., BP2876) | | L1 | 470µH | Through-hole or Shielded SMD, 1.5A | | D1 | SS34 | Schottky, 40V/3A | | C3 (Output) | 220µF / 35V | Low ESR Electrolytic | | C4 (Output HF) | 10µF / 35V | Ceramic | | R_FB_Top | 39kΩ | 1% tolerance | | R_FB_Bottom | 1kΩ | 1% tolerance | f4901 1.1a 24v schematic
On an electrical schematic, the letter prefix stands for Fuse .
The F4901 is almost always placed in with the load on the high-side (power supply line). Typical Schematic Diagram A healthy fuse will beep or register a
The fuse is fed by the primary high-voltage system DC rail (typically generated from the AC adapter input).
The downstream circuit has a short to ground, or a component has failed. This keeps F4901 stuck in its high-resistance, tripped state. Typical Schematic Diagram The fuse is fed by
The fuse sits directly inline with the main power path. In standard schematics, it is represented by a wave symbol or a small rectangular box bridging two nodes. If a downstream component fails and pulls excess current, this component snaps the circuit line safely. 4. Downstream Smoothing and Load
These are typically Surface Mount Devices (SMD), often in 0603 or 1206 packages, allowing for compact PCB designs.
Working on laptop power circuits involves risks. Always adhere to these safety protocols: