When either of the front doors [C] are opened, or when the front edge cover [A] is removed, the safety switches [B] disable the laser unit to prevent it from accidentally firing. The safety switches are installed on the 5V power supply line from the PSU that supplies power to the laser unit.
In this machine, the mechanism that enables laser operation is a 24V line, interrupted using a 5V relay and then 24V is dropped to +5V by a regulator. To ensure the safety of the machine operators and service technicians, six switches prevent the laser beams from switching on accidentally. When either front door or the toner bank door (front cover) is opened, or when the front edge cover is removed, the +5V line connecting each LD driver on the LD control board is disconnected to disable the laser units.