Kyocera PF-750 Service Manual page 47

Detecting the paper level
The lift rises as paper in the cassette is used.
When the remaining number of sheets in either right or left cassette reduces to around 100 to 250 sheets, the projection
on the lift belt assembly pushes against the sensor lever which turns the relevant paper level detection sensor 1 or 2
(PLDSENS1/2) on.
When both paper level detection sensors 1 and 2 (PLDSENS1/2) have turned on, the message [Low on paper.] is shown
on the machine message display. This message is not shown when only one of them is on.
As more copies are made with the message on, paper path sensors 1, 2 and 3 (PPSENS1/2/3) or the paper empty sensor
(PESENS) start to detect absence of paper, and the message [Add paper in cassette 3.(Add paper cassette 3.)] is shown.
Sensor lever
Lift belt assembly
Figure 2-1-8 Detecting the paper level
PLDSENS1
PFMPWB
Figure 2-1-9 Paper level detection system block diagram
Paper level
detection sensor
1 or 2 (PLDSENS1/2)
PLDSENS2
CN2-1
CN3-3
5H0
2-1-5