Development Bias - Ricoh FT8680 Service Manual

31 July 1995

6.4 DEVELOPMENT BIAS

6.4.1 Bias Power Pack
PWM Duty Cycle = t2/t1 x 100 (%)
Output = 10 x PWM Duty Cycle (V)
TRIG1 TRIG2
L H
H L
L L
H H
The bias power pack has three input terminals. Two of them are used as the
output selector as shown in the table. When both terminals are low, the
output can be controlled by the other input terminal which receives the PWM
signal from the main PCB.
+800 and +100 V are used to calibrate the drum potential sensor in the
process control data initialization.
Potential Sensor
Bias
P.P.
OUTPUT (V)
+800
+100
depends on the PWM signal
0
RA1
Drum Current
Detection PCB
TRIG 1 (800V)
TRIG 2 (100V)
PWM
Sensor
2-41
DEVELOPMENT
RA2
Relay
Main PCB
A171D529.wmf
A171D525.wmf