Lsu (Laser Scanner Unit) - Samsung CLP-775ND Series Service Manual

2. Product spec and feature

2.2.4.4. LSU (Laser Scanner Unit)

It is the core part of the LBP which switches from the video data received to the controller to the electrostatic latent image
on the OPC drum by controlling laser beam, exposing OPC drum, and turning principle of polygon mirror. The OPC drum is
turned with the paper feeding speed. The /HSYNC signal is created when the laser beam from LSU reaches the end of the
polygon mirror, and the signal is sent to the controller. The controller detects the /HSYNC signal to adjust the vertical line of
the image on paper. In other words, after the /HSYNC signal is detected, the image data is sent to the LSU to adjust the left
margin on paper. The one side of the polygon mirror is one line for scanning.
Photo Diode
LD Driver circit
Protector panel
Trouble
Polygon Motor Error
Hsync Error
2-15
LD(Laser Diode)
Failure Analysis
The Rotation of Polygon Motor can not reach stable.
Though the rotation of Polygon Motor reach stable, the signal of Hsync is not occurred.
Polygon Mirror
Polygon Motor
Motor Driver
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OPC Drum