Appendix C: Theory of operation
POR sequence
At power on, the engine code goes through a series of tests to verify hardware integrity. If a hardware failure is detected,
it will be reported to the printer. If the POR sequence cannot be completed successfully, the printer may post an error
message identifying service may be needed.
Printer control
The printer uses a single processor for both RIP and engine functions. The raster image processor (RIP) code performs
system responsibilities such as PC connection, LAN, ISP attachments, and bitmap generation. The engine code performs
tasks related to the operation of the electrical and mechanical device systems such as motors, lasers, power supplies,
and fusers. The NVRAMs are located on the controller board and control panel, replacement of either the controller
board or control panel will pull or mirror NVRAM data from each other.
Paper path information
Input tray
Component functions for feeding from the tray:
•
Tray present sensor—Detects if the tray is inserted
•
Media present sensor—Detects whether the tray is empty or not.
•
Pick/Lift motor—Supplies the mechanical power requirements of the lift plate and the pick rollers.
When feeding media, the front part of the lift plate is raised, pressing the media to the pick rollers. The pick rollers
rotate to feed the media to the separator rolls. The separator rolls rotate in a direction opposite to the pick rollers. This
ensures that sheets are fed one at a time. The media is then fed to the secondary input roller and then to the first input
roller.
Appendix C: Theory of operation
291
4514-630, -635, -636, -638, -639, -649
First input roller
Secondary input
roller
Separator roll
Pick rollers
Option tray