Charging Control - Konica Minolta 7020 Service Manual

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CORONA UNIT
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Charging Control

1
24VDC
24VDC
PGND
PGND
SGND
5VDC
DCPS
The HV (high voltage unit) carries out charging by
outputting a high voltage onto the charging wire.
The HV is controlled by analog control signals output from
the PRDB (printer drive board).
1. Operation
The HV comes ON together with M1 (main motor),
and goes OFF at a predetermined time interval after
transfer output for the final sheet goes OFF.
a. Charging
An inverter boosts the 24VDC power from the DCPS,
generating a high negative DC voltage that is
discharged from the charging wire.
b. Grid voltage
The HV applies grid voltage to the charging control
plate.
24VDC
24VDC
PGND
PGND
M1 LOCK SIG
M1
M1 CLK
M1 CONT
5VDC
SGND
PGND
24VDC
CHARGING
C CONT
C SHIFT
G SHIFT
F(C) SIG GRID
HV
PRDB
2. Signal
a. Input signal
(1) F (C) SIG (HV −> PRDB)
[L] if charge output has been forcibly switched OFF
owing to detection of spark or occurrence of output
short.
b. Output signals
(1) C CONT (PRDB −> HV)
Charge voltage and grid voltage ON/OFF control
signal.
[L]: Charge and grid voltages ON
[H]: Charge and grid voltages OFF
(2) C SHIFT (PRDB −> HV)
Analog signal from PRDB; controls the output level
of the charging corona unit.
C SHIFT output range
Charging output range
(3) G SHIFT (PRDB −> HV)
Analog signal from PRDB; controls the output level
of the grid voltage.
1
G SHIFT output range
Grid voltage output
range
2-F-2
4 to 10V
–100 to –650µA
4 to 10V
–450 to –1090V