The 5700ACO Automatic Changeovers are intended for use with two 5700MSC Master Clock/Sync Generators. The 5700ACO system uses mechanically latching relays to ensure maximum reliability and minimal disruption in the event of any failure, even power failures. The complete system provides the highest level of security for television station video and time synchronization systems. The 5700ACO is a 2RU ACO for all outputs of the 5700MSC. Two power supplies are included as a standard feature, to alleviate any single point of failure concerns. There are three switches behind the front panel for added security. There is an AUTO/MANUAL switch, a GPI/FRONT PANEL switch and an A/B select switch for manual changeover. In automatic mode, all signals from both 5700MSC are monitored to detect any abnormal signals. For example, if a level, pulse width, phase, time code error or other abnormality is detected, the 5700ACO's circuitry will trigger and the entire bank of signals will be switched to the backup 5700MSC. In manual mode the changeover can be operated from a GPI or from the front panel switch. LEDs provide status information as to the health of the two 5700MSC, together with indication as to which one is active. In addition, two GPO outputs indicate which master is active and when the inputs from both masters are not the same.