Oki OKIOFFICE44 Service Manual page 291

5-7 Photosensors
The photosensors mounted on this circuit board/sensor board supervise the paper running state
during printing. These four photosensors are used in this printer as listed below. All of their
outputs enter IOGA for referring to and processing by the CPU.
1) PS1 (photosensor 1): TNRSNS
Detects the lack of the toner.
2) PS2 (photosensor 2): PSIN
Detects the leading part of the paper and gives the supervision timing for switching from
hopping operation to feeding operation. Supervises the paper running state and the paper
size according to the paper arrival time and running time.
3) PS3 (photosensor 3): PSOUT
Supervises the paper feed according to the time of arrival at the sensor and the time of
passage of paper.
4) PS4 (photosensor 4): WRSNS
Detects the leading part of sensor.
Supervises the paper running state.
5-8 Cover open circuit
The cover open circuit consists of CVSW. When the Cover-Main is opened, the cover open
microswitch (CVSW) on the OLHV/TLHV board is turned off to cut the supply of H5V to the
high-voltage power supply circuit. As a result all high-voltage outputs are interrupted. At the
same time, the CVOPN-N signal is sent to the control board to notify it the off state of the
microswitch, and the control board performs the cover open processing.
Board Descriptions A - 49 OKIOFFICE 44 Serv. Man., P/N 59276801