Charging Control - Minolta Di850 Service Manual

CORONA UNIT SECTION

[3] Charging Control

C CONT1
C CONT2
C SHIFT
SGND
G SHIFT
PRCB
MS2 MS1
24VDC
PGND
DCPS2
Charging control is conducted by serial data transmit-
ted 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
applied 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
corona unit and charging grid.
b. Grid voltage
The grid voltage is output from HV1 to the charg-
ing plate.
C SIG
CHARGING
HV1
2-F-2
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 con-
trolled 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
according to the duty ratio of the pulse (PWM)
signal sent from the PRCB.
G SHIFT duty
Grid voltage output range -400 V to -1000 V
20% to 80%
20% to 80%