How to Troubleshoot Fiber-Optic Cable

By Dan Ketchum

Fiber-optic cables are extremely efficient, but must be handled with care.
i fiber optic computer cables image by Andrew Brown from

Fiber-optic cables transmit large quantities of data at the speed of light. Devices such as modems, routers, televisions and personal computers use fiber-optic cables to receive and transmit all sorts of information. The fibers in these cables are made from fragile glass and many common problems result from tension, pressure or stress on the fibers. Dead, frayed or otherwise damaged cables usually cannot be fixed at home and must be replaced.

Cable Inspection

Inspect the fiber-optic cable by following it along its length. Look for bends in the cable, which obstruct the cable's optical fibers. Gently straighten any unnecessary bends.

Remove any objects resting on top of, or otherwise putting pressure on, the cable.

Check for excess tension in the cable. Fiber-optic cables should have some slack, as tension causes stress on the fibers. Slacken any cables that are pulled tightly.

Shorten cable spans that seem excessively long by placing connected devices closer together and using shorter fiber-optic cables.

Identify any splits, rips or tears in the cable. Replace any damaged cables with new fiber optics.

Direct a laser pointer into the connector at one end the fiber-optic cable. If no light shines through the other end, the cable is dead and needs to be replaced.

Connection Troubleshooting

Locate the point at which the fiber-optic cable connects to a device, whether it be a modem, router, television or other piece of electronic equipment.

Check the connection. If the connection is loose, firmly secure the cable to the electronic device.

Inspect the cable's connectors. Spray the connector with compressed canned air to remove dust and foreign particles.

Disconnect the fiber-optic cable and reconnect it to the device if simply tightening the connection fails to remedy the problem.

Investigate the point of access for any fiber-optic cable that enters your home from the outside. Remove any foreign elements that could obstruct or place stress on the cable.