If you see 24V on the input side but near 0V on the output, the fuse is tripped.
The F4901 1.1A 24V schematic operates as follows: f4901 1.1a 24v schematic
: High-speed switch that drives the primary side of the transformer. Isolation & Output Stage Transformer : Steps down the voltage and provides galvanic isolation. Schottky Diode : Rectifies the output back to DC. Filter Capacitors & Inductor : Smooths the output to a stable 24V. Feedback Loop Optocoupler & TL431 If you see 24V on the input side
If you are troubleshooting a dead laptop or a "Fan Error," check this fuse for continuity. In Wistron designs, fuses with numbers starting in the "4900" range are often grouped near power delivery circuits. F4901 1.1a 24v Schematic f4901 1.1a 24v schematic