HP LaserJet M9040/M9050 Service Manual - Page 131

the problem in the failure loads, wait about two minutes, and then turn on the product. The circuit contains a power fuse (F1) which breaks and cuts off the power supply if overcurrent flows through the AC line. Figure 5-11 Power supply Scanner controller circuit The CPU on the SCB controls the operation sequences of the scan engine. When the dc power is supplied to the scanner controller, the CPU starts to control the scan engine. When the scan engine is in standby status, the CPU outputs signals to drive each load of charge-coupled devices (CCDs), motors, solenoids, and scanning lamps based on a scan command from the CP. ● CPU (IC7): According to the control programs stored in the ROM (IC5), the CPU performs: ◦ image scanner sequence control ◦ communication with the copy processor control ◦ pickup motor and delivery motor drives control ● GA (Gate Array) (IC4): According to commands from the CPU, the GA performs: ◦ scanning lamp drive control ◦ sensors, switches, and LEDs control ◦ solenoids control ◦ fan motors control ◦ flatbed document scanning motor control ENWW Basic operation 113