Charge Corona Circuit - Ricoh A219 Service Manual

2.3 CHARGE CORONA CIRCUIT

Main Board
24 V
C N 1 0 2 - 7
G N D
C N 1 0 2 - 6
C Trigger
C N 1 0 2 - 5
T Trigger
C N 1 0 2 - 4
B - P W M
C N 1 0 2 - 3
S Trigger
C N 1 0 2 - 2
5 V
4.7 k
C N 1 0 2 - 1
The main board supplies +24 V to the high voltage supply board at CN102-7.
After the ! key is pressed, the CPU drops CN102-5 from +5V to LOW.
This activates the charge corona circuit which applies a high negative voltage
of approximately –5 k volts to the charge corona wire. The corona wire then
generates a negative corona charge.
The grid plate limits the charge voltage to ensure that the charge does not
fluctuate and that an even charge is applied to the entire drum surface. The
grid plate is connected to ground through a zener diode in the high voltage
supply unit. The grid plate drains any charge in excess of –910 V, which is
discharged to ground through the zener diode.
SM
CÓPIA NÃO CONTROLADA
High Voltage Supply Board
D C / D C
Converter
D C / D C
Converter
D C / D C
Converter
Zener
Diode
D C / D C
Converter
Protection
Circuit
2-5
CÓPIA NÃO CONTROLADA
CHARGE
G C
Drum
B
S
T
A219D506.wmf
A219