Canon FAXPHONE L75 Service Manual

Also see for FAXPHONE L75: User guide Specifications Setup sheet Software user's guide

Contents

Canon FAXPHONE L75 Service Manual Manual pdf 58 page image

2-17LASER CLASS 1060P Chapter 2: Technical Reference6.2 Circuit Board Componentsa) System control sectionThe system controller is made up of the following components, and controls the entire fax system.a-1) MPU (Micro Processor Unit) (IC1)The main functions of the NEC μPD703100AGJ-33-UEN MPU are as follows:• 32 bit CPU• 24 bit address bus• 16 bit data bus• DMA control• A/D converter• Software CODEC• Interrupt control unita-2) System controller (IC10)The system controller is a gate array for controlling MPU peripheral devices. The main functions of thesystem controller are as follows:• Printer resolution conversion (Smoothing)• LBP video interfaceThe LBP video interface transfers print signals to or from the printer controller and sends them to theMPU. The interface transmits an image signal (nVDO) and a vertical sync signal (nTOP) to the printersection, receives a horizontal sync signal (nBD) and printer section status from the printer section andtransfers them to the MPU.• OPCNT serial interface• DRAM/SRAM controllerControls DRAM/SRAM read/write and refreshing.• Document feed motor control• Reduction in vertical scanning• Recording decoder• RTC (Real Time Clock) controlThe RTC IC is backed up by lithium battery, and counts the date and time.• SRAMSRAM is backed up by lithium battery. SRAM holds data registered for system control and communi-cations management information.a-3) Main ROM (SOC1)This 8 Mbit ROM contains the control programs (e.g. operation panel, scanner and communicationssection etc.) for this fax.a-4) DRAM (IC4)This 64 Mbit is used as memory for storing image data, and as an MPU work area.