Ricoh FT 4015 - Development Bias Circuit

5.5 DEVELOPMENT BIAS CIRCUIT
The main board supplies +24 volts to the high voltage supply board from
CN102-7. When the  key is pressed, the CPU starts sending the bias
trigger pulses from CN102-3. This energizes the development bias circuit
within the high voltage supply board, which applies a high negative voltage to
the development roller. The development bias is applied whenever the drum
is rotating.
DC/DC
Converter
CN102-7
Drum
B
Zener
Diode
Protection
Circuit
DC/DC
Converter
DC/DC
Converter
DC/DC
Converter
GND
CN102-6
CN102-4
CN102-3
CN102-2
CN102-1
24 V
C Trigger
T Trigger
B-PWM
S Trigger
S
T
GC
5 V
4.7 k
Main Board High Voltage Supply Board
CN102-5
A219D506-2.wmf
DEVELOPMENT 20 December 1996
2-24