A display apparatus comprising: an optical communication interface configured to communicate with an electronic device through an optical cable ; a processor ; and an outputter , the display apparatus being characterised in that the processor is configured to: based on an optical signal including at least one signal among an image signal and a sound signal being received from the electronic device through the optical communication interface, measure a strength of the received optical signal, based on the measured strength of the optical signal being smaller than a first threshold value and greater than or equal to a second threshold value smaller than the first threshold value, transmit a control signal for increasing a strength of transmission of the optical signal of the electronic device to the electronic device, based on the measured strength of the optical signal being smaller than the second threshold value, determine that the optical cable is defective, and output, through the outputter, a notification indicating that the optical cable is defective, and based on the strength of the optical signal measured after transmitting the control signal to the electronic device being identical to the strength of the optical signal measured before transmitting the control signal to the electronic device, determine that the optical cable is defective. an optical communication interface configured to communicate with an electronic device through an optical cable ; a processor ; and an outputter , the display apparatus being characterised in that the processor is configured to: based on an optical signal including at least one signal among an image signal and a sound signal being received from the electronic device through the optical communication interface, measure a strength of the received optical signal, based on the measured strength of the optical signal being smaller than a first threshold value and greater than or equal to a second threshold value smaller than the first threshold value, transmit a control signal for increasing a strength of transmission of the optical signal of the electronic device to the electronic device, based on the measured strength of the optical signal being smaller than the second threshold value, determine that the optical cable is defective, and output, through the outputter, a notification indicating that the optical cable is defective, and based on the strength of the optical signal measured after transmitting the control signal to the electronic device being identical to the strength of the optical signal measured before transmitting the control signal to the electronic device, determine that the optical cable is defective. based on an optical signal including at least one signal among an image signal and a sound signal being received from the electronic device through the optical communication interface, measure a strength of the received optical signal, based on the measured strength of the optical signal being smaller than a first threshold value and greater than or equal to a second threshold value smaller than the first threshold value, transmit a control signal for increasing a strength of transmission of the optical signal of the electronic device to the electronic device, based on the measured strength of the optical signal being smaller than the second threshold value, determine that the optical cable is defective, and output, through the outputter, a notification indicating that the optical cable is defective, and based on the strength of the optical signal measured after transmitting the control signal to the electronic device being identical to the strength of the optical signal measured before transmitting the control signal to the electronic device, determine that the optical cable is defective. <EOS>