Charging Control - Konica Minolta 7085/FORCE 85 Service Manual

CORONA UNIT SECTION

[3] Charging Control

C CONT1
C CONT2
C SHIFT
SGND
G SHIFT
PRCB
24VDC
PGND
DCPS2
Charging control is conducted by serial data transmitted
3
from PRCB (printer control board) to HV1 (high voltage
unit 1). The applied voltage for the charging wires are
supplied by HV1.
1. Operation
a. Charging
A Scorotron charging method is used. 24 VDC
supplied from DCPS2 is raised to a negative DC
voltage which is then discharged after being ap-
plied to the charging wire.
When the front door of this machine opens or
closes, MS1 (interlock 1) or MS2 (interlock 2)
operates to interrupt the DC power supply to HV1,
stopping the voltage supply to the charging co-
rona unit and charging grid.
b. Grid voltage
The grid voltage is output from HV1 to the charg-
ing plate.
MODEL
7075/7085
SERVICE HANDBOOK
C SIG
CHARGING
MS2 MS1
HV1
MANUAL
2. Signals
a. Input signal
(1) C SIG (HV1 to PRCB)
Leak or short detection signal.
[L]: Normal
[H]: Abnormal
b. Output signals
(1) C CONT1, 2 (PRCB to HV1)
Charging 1/2 output ON/OF control signal.
[L]: Charging voltage ON
[H]: Charging voltage OFF
(2) C SHIFT (PRCB to HV1)
Charging corona unit output level control signal.
The output to the charging corona unit is control-
led according to the duty ratio of the pulse (PWM)
signal sent from the PRCB.
C SHIFT duty
Charging output range -500µA to -1900µA
(3) G SHIFT (PRCB to HV1)
Charging grid output level control signal.
The output to the charging grid is controlled ac-
cording to the duty ratio of the pulse (PWM) sig-
nal sent from the PRCB.
G SHIFT duty
Grid voltage output range -400 V to -1000 V
REVISED EDITION
2 - F - 2
Jan. 2002
3
20% to 80%
20% to 80%
DATE PAGE
2-F-2 REPLACEMENT
METHOD