8-22 Phaser 4400 Laser Printer Service ManualEngine Logic Board and Front PanelFunctionsThe Engine Logic Board performs eight main functions: Communicates with the Image Processor. Controls the print sequence. Controls the Fuser Assembly, Laser Assembly, and Drive components. Distributes low DC voltages to various printer components. Monitors printer status. Maintains a running print count. Writes the NVRAM settings. Controls printer options.The Engine Logic Board uses a 32 bit microcomputer and Application SpecificIntegrated Circuits (ASICs). The 32 bit microcomputer includes: ROM, RAM, a16 bit integrated timer, a programmable timing pattern controller, a watch dog timer,serial communication interfaces, an A/D converter, a D/A converter, I/O ports, aDMA controller, and a refresh controller.Image Processor BoardThe Image Processor (IP) is one of the major elements that make up the Phaser 4400printer. The primary function of the Image Process is to receive Host data through oneof the following available ports (Parallel, USB, or Ethernet). The received host data isbuffered and stored and sent to the print engine in a rasterized format.The secondary function of the Image Processor is to provide print control, front panelcontrol, configuration setup, error reporting and job recovery.Before the IP can receive and process data it must first pass the Power On Self Test(POST). This test process verifies proper operation of the Image Processor andprepares it for processing the host data by putting the Image Processor in a knownstate.The Image Processor connects to the Engine Logic Board directly. The Front Panel isconnected to the Image Processor and signals pass through the Engine Logic Boardvia the Image Processor.5 VDC PWBThis board converts 24 VDC from the LVPS to 5 VDC, which it supplies to the ImageProcessor board.
