Check Fiber Cables : Look for visible damage, sharp bends, or loose connectors. Clean Connectors : Use lint-free wipes and isopropyl alcohol to remove dust or oil. Scratches on the fiber can affect the signal's performance, as even the slightest. This document presents a troubleshooting guide for fiber optic cables once deployed and in regular use. It also includes a list of common fault location items. Start with the simplest, fastest checks (visual inspection, cleaning, cable routing) and only move to instrumentation (power meter, VFL, OTDR) when those steps don't clear the fault. This saves time and prevents needless part swaps. An OTDR (optical time domain reflectometer) is basically an optical radar that send a pulse up the line and analyses the echo. OTDRs are good at examining long links, up to 100 Km or more. However, in real-world installations, whether underground, aerial, or in harsh industrial environments, fiber cables can and do fail.
