Charger quality control during mass production involves more than final inspection. A professional charger factory controls the process from incoming components and BOM management through PCBA assembly, electrical testing, aging, final inspection, packaging, and production traceability. The goal is to ensure that every production batch matches the approved design and maintains consistent electrical, safety, and reliability performance.

A USB-C charger may make a buzzing or whining sound because magnetic components such as transformers and inductors can vibrate during high-frequency switching. The sound can be more noticeable at no load or light load when the charger enters burst-mode operation. A faint, stable sound may be normal, while loud or sudden noise combined with overheating or charging interruptions should be investigated.