HP 4300 Service Manual - Page 114

-sheet feeder lifting mechanism, stack position sensor SR2 detects media.

Page 114 highlights

1,500-sheet feeder lifting mechanism The lifting mechanism maintains the media stack surface at a specific position inside the 1,500sheet feeder. This allows the feeder to perform a stabilized pickup operation regardless of the size of the media loaded in the feeder. The lift plate inside of the feeder is lifted by two wire cables. A motor (M1) winds these wires up using pulleys in the feeder. When the front door of the feeder is opened, the pulley gears and the motor gear are disengaged and the lift plate lowers under its own weight. The lifting mechanism is active (the plate is in the raised position) when it is signaled by the DC controller PCA, the front door is closed, or during the print operation. The 1,500-sheet feeder control PCA driver stops the motor (M1) when the 1,500-sheet feeder paper stack position sensor (SR2) detects media. If the 1,500-sheet feeder paper stack position sensor (SR2) does not detect media within about 30 seconds after the start of the lift operation, the paper-deck driver PCA detects a lifter motor failure and sends a signal to the DC controller PCA. An error message appears on the controlpanel display. Figure 26. 1,500-sheet feeder lifting mechanism 94 Theory of operation Q2431-90912

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94
Theory of operation
Q2431-90912
1,500-sheet feeder lifting mechanism
The lifting mechanism maintains the media stack surface at a specific position inside the 1,500-
sheet feeder. This allows the feeder to perform a stabilized pickup operation regardless of the
size of the media loaded in the feeder. The lift plate inside of the feeder is lifted by two wire
cables. A motor (M1) winds these wires up using pulleys in the feeder. When the front door of the
feeder is opened, the pulley gears and the motor gear are disengaged and the lift plate lowers
under its own weight. The lifting mechanism is active (the plate is in the raised position) when it
is signaled by the DC controller PCA, the front door is closed, or during the print operation. The
1,500-sheet feeder control PCA driver stops the motor (M1) when the 1,500-sheet feeder paper
stack position sensor (SR2) detects media.
If the 1,500-sheet feeder paper stack position sensor (SR2) does not detect media within about
30 seconds after the start of the lift operation, the paper-deck driver PCA detects a lifter motor
failure and sends a signal to the DC controller PCA. An error message appears on the control-
panel display.
Figure 26.
1,500-sheet feeder lifting mechanism