HP LaserJet M1005 Service Manual - Page 65

NOTE In other HP LaserJet devices, the ECU and power functions are combined onto one PCA known as the controller PCA or the DC controller PCA. In the HP LaserJet M1005 MFP, the control functions are primarily relegated to the ECU PCA and the power functions to the powersupply assembly PCA. The ECU controls the following systems and functions: ● Device engine control ● paper-motion monitoring and control (printing) ● motor ● Device laser/scanner unit The power-supply assembly provides the following functions to the power system: ● ac power distribution ● dc power distribution ● overcurrent/overvoltage protection ● high-voltage power distribution Device engine control system Paper motion monitoring and control. The ECU controls paper motion in the device by continuously monitoring the two paper sensors and coordinating the timing with the other print processes. Motor. The ECU controls the motor. The motor drives all of the device paper movement. Device laser/scanner unit The ECU sends signals to the laser/scanner assembly to modulate the laser-diode on and off modes and to drive the laser/scanner motor. Power system on the power-supply assembly The ac, dc, and high-voltage power supply circuits are all provided by the power-supply assembly. Ac power distribution The ac power circuitry supplies ac voltage whenever the power cord is connected to the ac power source and the power switch is on. The ac voltage is distributed to the dc power supply circuitry and to the ac driver circuitry, which controls ac voltage to the fuser assembly heating element. Dc power distribution The dc power distribution circuitry, located on the engine power assembly, distributes +3.3 Vdc, +5 Vdc, and +24 Vdc as follows: Table 5-3 Dc power distribution +3.3 Vdc +24 Vdc ECU, sensors, formatter Main motor, laser/scanner motor, solenoid, high-voltage power supply, fuser, safety circuit, door switch ENWW Device functions 49