Specifications

2.3 CHARGE CORONA CIRCUIT
The main board supplies +24 volts to the CC/Grid/Bias power pack at CN1-1
as the power supply source. About 0.44 seconds after the Start key is
pressed, the CPU drops CN1-3 from +24 volts to 0 volts. This energizes the
charge corona circuit within the CC/Grid/Bias power pack, which applies a
high negative voltage of approximately –5.6 kv to the charge corona wire.
The corona wire then generates a negative corona charge.
The grid limits the charge voltage to ensure that the charge does not fluctuate
and an even charge is applied to the drum surface.
The grid trigger pulse applied to CN1-5 is a pulse width modulated signal
(PWM signal). This signal is not only a trigger signal; it also changes the
voltage level of the grid. As the width of the pulse applied increases, the
voltage of the grid also increases. The CPU monitors the grid voltage at
CN1-7 and controls the width of the grid trigger pulses based on this
feedback.
VA [24]
VC [5]
CC Trig [ 24]
Grid Trig (PWM) [ 0 0/5]
Grid FB
GND [0]
Main Board (PCB 1)
CN112-8
CN112-7
CN112-6
CN112-5
CN112-4
CN112-3
CN112-2
CN112-1
TC
TB
CN1-1
CN1-2
CN1-3
CN1-4
CN1-5
CN1-6
CN1-7
CN1-8
TG
Grid
Charge
Corona Wire
Development
Roller
CC/Grid/Bias
Power Pack
(P1)
1 December 1990
2-6