Oki OKIOFFICE84 Maintenance Manual page 297

2) The CB2 output voltage is stabilized by keeping the primary flyback voltage
obtained by switching operation of Q1 at a constant voltage by D7 and D6 and D5.
2. 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 IOGA4 for referring to and processing by the IOGA4
(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.
3. 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
interruptted. 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 process-
ing.
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P2H
40672201TH Rev. 4