Specifications

5.5 DEVELOPMENT BIAS CIRCUIT
The main board supplies +24 volts to the CC/Grid/Bias power pack at CN1-1
as the power supply source. When the Start key is pressed, the CPU starts
sending the bias trigger pulse to CN1-4. This energizes the development bias
circuit within the CC/Grid/Bias power pack, which applies a high negative
voltage to the development roller. The development bias is applied whenever
the drum is rotating except when the Vr pattern is developed.
The bias trigger pulse applied to CN1-4 is a pulse width modulated signal
(PWM signal). This signal is also used to change the voltage level of the
development roller. As the width of the trigger pulses increase, the voltage of
the development roller also increases. The CPU monitors the development
bias voltage at CN1-6 and controls the width of the bias trigger pulses based
on this feedback.
VA [24]
VC [5]
Bias 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)
Bias Trig (PWM) [ 0 0/5]
1 December 1990
2-32