Nosignal

Nosignal is a common status displayed by video displays such as televisions, computer monitors, and projectors when the device is not receiving a valid video input. The message may appear as text such as “No Signal” or “No Input,” or as a placeholder image. It indicates that the expected video data is not present in the signal path, rather than revealing a specific fault in the display itself.

Causes of nosignal include problems in the signal path, the source device, or the display’s input configuration. Common examples are the source device being turned off or in standby, a disconnected or damaged video cable, an input selector not matching the actual connection, or incompatible resolution or refresh rate settings. Additional causes can include HDCP/EDID handshake failures between devices, the use of adapters or splitters, or issues with long or poor-quality cables. In some cases, nosignal appears briefly after waking devices from sleep until connections are re-established.

Troubleshooting typically involves verifying power to source devices, ensuring the correct input is selected, reseating or replacing cables, testing with a different port or another device, and adjusting the display or source settings to a compatible resolution and refresh rate. If the problem persists across multiple inputs and devices, the issue may reside in hardware such as ports, cables, or the source device, and professional service may be required.

In broadcasting and surveillance contexts, nosignal denotes an ongoing loss of a video feed between equipment, requiring diagnosis along the signal chain from source to display.