What is the role of the filter capacitor on a hard drive PCB?

The filter capacitor on a hard drive PCB is used to smooth out fluctuations in the power supply. The filter capacitor acts as a buffer, storing and releasing electrical energy as needed to maintain a stable voltage. The filter capacitor is typically located near the power input of the hard drive, as this is where fluctuations in the power supply are most likely to occur. The filter capacitor is an essential component for the performance and longevity of the hard drive, as it helps to prevent damage from voltage spikes and other electrical disturbances.