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3: Operation
3-48
Colorwriter LSR 2000 Printer
Service Guide
Figure 3-36
Voltage applied to primary charging roller
Generation of developing bias
When the print sequence starts, the primary charging voltage
(AC/DC) is applied and the toner cartridge is pressed against the
photosensitive drum and the developing cylinder is rotated. Then
the high-voltage control IC (IC1003) on the high-voltage power
supply PCB sets the developing bias dc drive signal (/DEVDC) to
“L” and applies the developing DC bias to the developing cylinder.
After the specified period of time has elapsed, the developing bias ac
drive signal (/DEVAVE) goes “L” and the voltage superimposing
Primary charging roller voltage generation circuit
/HV1PWM
DC voltage
generation
circuit
Voltage
conversion
circuit
Voltage
detection
circuit
/HV1DC0
/HV1DC1
Switching
circuit
Constant voltage circuit
HVFre1
Constant current
controller circuit
Sign wave
generation
circuit
Amplification
circuit
AC voltage
generation
circuit
Current
detection
circuit
/HV1AC1
Voltage
selection
circuit
Voltage
ON/OFF
circuit
/HV1AC0
High-voltage power supply PCB
Mechanical
controller
PCB
(High-voltage
control IC)
IC1003
HVFre2
HVFre1, 2 are pulse signals
Overlapping
Primary
charging roller
Integral circuit