Oce 3121 Technical & Service Manual page 207

Functional description
1 Limiting the charging bias
Outline
The bias for the charging roller is controlled by the power supply PBA, follow-
ing the instructions from the DC control PBA.
In addition, an AC bias is applied to the charging roller to ensure stable charg-
ing.
The power supply PBA serves the following functions:
Limiting the DC bias to a specific voltage
I
Limiting the AC bias to a specific current
I
Composite power supply PCB
J209-B6
J102-B5
DC controller PCB
ed.1
T101
Rectification
T101
Drive
DC
circuit
current
setection
Q605 CPU
J209-B2
J102-B9
CPU
IC101
Primary charging
T300
AC component
current detection
AC drive
circuit
Frequency
division
J209-A4~A9
J102-A1~A7
assembly
Photo-
sensitive
drum
Drum ambient
temperature detection
02 Charging 501