Epson EPL-N4000, Service Manual

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EPSON EPL-N4000/EPL-N4000+ Chapter 2 Operating Principles
Rev.B 79
2.7 Printer Control
Printer Control is a broad term that is used to describe the printer
resources that monitor and control the actions and operations of the
printer; from warm-up, through the print cycle, to machine error
detection.
The center of printer control for the printer base engine is the Machine
Control Unit PWB, or MCU PWB. The MCU contains an 8 bit
microcomputer. The MCU contains ASICs (Application Specific
Integrated Circuits) for image data transfer and communication control,
ROM, RAM, a 16 bit integrated timer, programmable timing pattern
control, a watch dog timer, serial communications interfaces, an A/D
converter, a D/A converter, I/O ports, and a DMA controller.
The MCU PWB provides the logic and information processing that is
necessary for the printer to function. Every electrical component within
the printer is connected either directly or indirectly to the MCU PWB.
Sensors in the printer send printer status information to the MCU. The
MCU processes that information and compares it to timing tables that
are stored in onboard ROM. Acting on the results of the processing, the
MCU sends commands to various printer components; switching on
motors, switching off voltages, signaling statuses. Non-Volatile RAM on
the MCU PWB stores adjustable operation parameters, such as Fuser
temperature and laser strength, that are used as reference during
printer operation.
Figure 2-38. Control Circuit Board
Controller