FC connectors need to be mated more carefully than push-pull type connectors due to the need to align the key, and due to the risk of scratching the fiber endface while inserting the ferrule into the jack. It has a screw-type lock that guarantees a firm and secure connection, an advantage in high-vibration situations. FC connectors are used in datacom, telecommunications, measurement. This document presents a troubleshooting guide for fiber optic cables once deployed and in regular use. These high-speed, high-capacity communication networks are increasingly replacing copper cables, offering superior performance and. A very common problem is that a connector is not fully engaged - often hard to notice in a crowded patch panel.