How to troubleshoot no video output or data communication failure after installation and wiring?

When there is no picture output or data communication failure, first check whether the receive/transmit relationship of the optical ports at both ends is paired and whether the transmit and receive wavelengths are consistent; then check whether the single-mode or multimode optical fiber matches the type of the optical module, and use an optical power meter to measure the received optical power and compare it against the specification of a receiver sensitivity better than -21 dBm; then check whether the BNC video connector is tightened and whether the 75 Ω input impedance matches the source device; finally check whether the wiring sequence of the data port is consistent with the settings of the three types RS-232, RS422 and RS485. For routine maintenance, it is recommended to switch off the power before inserting or removing the optical port, to clean the end faces regularly and to re-measure the optical power, and to keep the inside of the enclosure dry and avoid condensation. If the abnormality persists, it is recommended to contact the manufacturer's technical support together with the device status.