HP Color LaserJet CM4730 Service Manual - Page 164

Block operation The blocks that make up the DC controller PCB include: ● CPU. The CPU is a single-chip microcomputer with built-in ROM and RAM. It controls the MFP engine sequence, ASIC, fuser, pickup motor and lifter motor, solenoids, sensors, and switches. ● ASIC. Interfaces with the IC, memory, and external devices. ● Motor driver ASIC. Controls each motor in response to commands from the CPU. ● Reset IC. Monitors voltage and resets the CPU and ASIC when the power is turned on. ● EEPROM. Stores backup data. Motors, fans, and environment sensor The MFP has ten motors, ten fans, and one environment sensor. Seven of the motors are DC motors; the other three are stepping motors. Figure 4-6 Motors and fans on page 145 shows the locations of the motors and fans. Table 4-2 Function of motors, fans, and environment sensor on page 146 explains the function of each component. Two of the stepping motors and six of the seven DC motors are used for paper feeding and image formation. The remaining stepping motor is the developing disengaging motor. The remaining two DC motors are fan motors. Since the MFP transfers an image in four colors in line onto the media, small changes in the rotational speed of the motor are likely to cause color misalignment. The DC motors used for image formation are precisely controlled to account for rotational speed fluctuation. 144 Chapter 4 Theory of operation ENWW