Why can the red LED light be seen from the DIGITAL OUT (OPTICAL) terminal?

The red LED light can be seen from DIGITAL OUT (OPTICAL) when the Digital Audio Connector Adapter is inserted to the TV without an optical cable connected.

To avoid the red LED light from  DIGITAL OUT (OPTICAL), connect an optical cable to the Digital Audio Connector Adapter or remove the Digital Audio Connector Adapter from the TV when no optical cable is connected.

NOTE: If the Digital Audio Connector Adapter is inserted without an optical cable, do not directly look at the optical light source emitted from the Digital Audio Connector Adapter because it may cause discomfort to your eye.

The Digital Audio Connector Adapter activates the Optical Output function and turns on the optical LED light.